"Math in pre-algebra can be tough but I know my stuff." ~Wonder
All you have to do for memorizing graphs is to look at the names. Take the pictograph for example it uses pictures. Same with bar graph. Now the histogram is the only one I find tricky the bars are connected and vertical.
I would suggest going online and looking at graph formats if you are struggling with it.
You can't blame the writer for what the characters say. — Truman Capote
What you're basically trying to do is solve one of the equations for a single variable and then using that first solved equation to solve the second one.
A simple case is this:
y = 3 x + y = 7
y is already solved for, so you stick 3 in for y in the second equation to get:
