y=x-2
y=-2x+7
Put it in your calculator, or sketch the picture on a graph. The slopes are 1 and -2, and they start on the Y-axis at -2 and 7, respectively. Now, when you sketch it, the point that the two lines intersect at is the solution. Put the horizontal coordinate in to x, and the vertical coordinate in to y, and verify that it is indeed correct.