SOLUTION: My daughter is frustrated in Algebra II (well all math in general that is). She was given homework in which I cannot assist her with; It's been about 25-years for me. I was good at

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Question 490180: My daughter is frustrated in Algebra II (well all math in general that is). She was given homework in which I cannot assist her with; It's been about 25-years for me. I was good at it, but need a refresher in order to assist her. Here is a simple graphing problem:
y = x - 2
y = -2x + 7
Her book seems to miss some of the steps and I don't remember what to do. According to the answers at the back of the book her graph was in error on one of the positive lines (on the x axis she began at -7). What is the correct way to solve this simple problem?
Found 2 solutions by Earlsdon, josmiceli:
Answer by Earlsdon(6294) (Show Source):
You can put this solution on YOUR website!
This is a "system of equations" or "simultaneous equations (at least, where I went to school)"
y = x-2 and
y = -2x+7
Now since y = y, you can just set the two equations equal to each other thus:
x-2 = -2x+7 and solve for x. Add 2x to both sides.
3x-2 = 7 Now add 2 to both sides.
3x = 9 Finally, divide both sides by 3.
x = 3 Now you must replace the x in either of the two given equations and solve for y.
y = -2x+7 Substitute x = 3.
y = -2(3)+7 Evaluate.
y = -6+7
y = 1
The solution is (3, 1)
Another way is to graph the two given equations and find the point of intersection (if any) of the two lines.

The lines intersect at (3, 1)

Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website!
All equations that look like these, that have the general form
, are straight lines.
Graphing amounts to finding a few of the points (x,y) that
lie on the given straight line.
The easiest way is to set and find
Then set and find

So, the point (2,0) is on the line
and

So, the point (0,-2) is on the line
Do the same thing with the other line