Pre-Algebra

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Fri Jan 23, 2009 3:17 am
Evi says...

So, yeah. Math has never been my strong point, and my parents are about as skilled as I am. I tremble at the sight of these problems. They're a piece of cake for you smart people, but my twelve-year-old mind is too tired to think straight.

9m-7m-5=17

Is there a property I should be using to simplify this?

And...

3t + 5
--------- = -5
8

Ick. Any help in showing a poor seventh grader the steps?

EDIT:

I have new problems! These first two, thanks to Jared and Snoink, are taken care of. Now, I've got word problems.

Anyone care to help me unravel them?

[s]There are two trees in a yard. One of them is 50 inches tall and grows at a rate of 2 inches per month. The other tree is 59 inches tall and grows at a rate of 1 inch per month. How many month will it take until both trees reach the same height?[/s] Solved. Thanks to Random.Thoughts, who rocks epically.

-And-

Roses cost \$15 for a dozen, or more in bought individually. You want to purchase 9 dozen and 6 individual roses for a party decoration. For the price of 9 dozen and 6 individual roses you can also purchase 51 individual roses. How much is one rose? How much money do you have to spend on the party decoration?

I would be able to do these if I new exactly which equation to use. How should I phrase it? They, obviously, have variables. I think each problem has two of the same variable, like two x's or two h's, but not an x and an h. If that makes any sense.

Help? I'll be forever grateful to you brilliant word-problem decipher-ers.

~Evi
Last edited by Evi on Sun Feb 01, 2009 10:55 pm, edited 5 times in total.
"Let's eat, Grandma!" as opposed to "Let's eat Grandma!": punctuation saves lives.

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Fri Jan 23, 2009 6:17 am
Snoink says...

Haha, for a second, I thought they were really two variables!

First off, I don't know what you mean by this:

3t + 5
--------- = -5
8

Can you express it any other way?

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Ubi caritas est vera, Deus ibi est.

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Fri Jan 23, 2009 1:19 pm

3t + 5
--------- = -5
8

First thing you're going to do is multiply the 8 from the denominator (bottom number on a fraction and from the -5, because what you do to one side, you do to the other.

3t + 5
--------- = -5 x 8
[s]8 x 8[/s]

Now your problem looks like this:

3t + 5 = -5 x 8 --> 3t + 5 = -40

Now you subtract a five from both sides:

3t + 5 - 5 = -40 - 5

And you end up with: 3t = -45

Then you divide the three on both sides:

3t = -45/3
-
3

And then
t = -45/3. I don't know what the answer is, cause I don't have my calcutator here, and it's 6 in the morning.

But, viola!

-Jared
Just write -- the rest of life will follow.

Would love help on this.

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Fri Jan 23, 2009 9:12 pm
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Evi says...

Eureka!

You both rock epically. I'm humbled by your genius. And, sorry, I though there were two variables. But I was tired, and my brain wasn't working properly. I think those were the only ones giving me trouble, but I might come across another...

Thanks again!
"Let's eat, Grandma!" as opposed to "Let's eat Grandma!": punctuation saves lives.

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Fri Jan 23, 2009 11:25 pm
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Snoink says...

Lol, no problem!

And Jared, you're lame.

-45/3 = -15

You don't need a calculator for that. Just look at a clock! XD
Ubi caritas est vera, Deus ibi est.

"The mark of your ignorance is the depth of your belief in injustice and tragedy. What the caterpillar calls the end of the world, the Master calls the butterfly." ~ Richard Bach

Moth and Myth <- My comic!

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Sun Feb 01, 2009 2:38 am
Evi says...

*Bump*

Hopefully, bumping is allowed in this forum. If it's not, please forgive me. I just didn't want to start a whole new thread.

The new problems I need help with are in the original post.
"Let's eat, Grandma!" as opposed to "Let's eat Grandma!": punctuation saves lives.

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Sun Feb 01, 2009 7:07 pm
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random.thoughts says...

Ok, the first one is easier then it seems! I'm going to do a general overview of the problem and if you need it more in dept then just PM me.

The first tree is 50in tall already. And it grows at a rate of 2x. (x=time in months) So the equation of growth with the tree would be 50+2x. The original height plus how much it could grow. The same is true for the second tree. 59< original hight. plus 1x (x=time in months). 59+1x. To find when the would be the same hight (hint hint equal to each other) just have the equations equal each other.

50+2x=59+1x
x=9
9 months.

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Sun Feb 01, 2009 10:55 pm
Evi says...

Ugh! That was simple. I'm just mathematically challegned, Random.

I still need help on the second one, if anyone can help me decipher it!
"Let's eat, Grandma!" as opposed to "Let's eat Grandma!": punctuation saves lives.

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Tue Feb 03, 2009 11:22 pm
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Snoink says...

For the rose problem, consider this:

You are given that one dozen roses cost \$15. So let's let d (for dozen) = 15.

(Recap: d = 15)

For individual roses, you aren't given a price. That is our variable. Let individual rose = i (for individual!)

(Recap: one individual rose = i)

Now, you know that if you buy nine dozen roses plus six individual roses, it's the same thing as buying 51 individual roses. So:

9d + 6i = 51i

EXCEPT! We know d, which is 15. So:

9*15 + 6i = 51i

...you should be able to figure out the rest.
Ubi caritas est vera, Deus ibi est.

"The mark of your ignorance is the depth of your belief in injustice and tragedy. What the caterpillar calls the end of the world, the Master calls the butterfly." ~ Richard Bach

Moth and Myth <- My comic!

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Fri Apr 10, 2009 8:11 pm
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chasingcolts21 says...

They pretty much told you everything, but if you need any more help, I specialize in Algebra Feel free to PM me.

It's super easy to me.
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