a. y = 40x + 70
b. The x int can be found by subbing in 0 for y and solving for x
0 = 40x + 70
-40x = 70
x = -70/40 reduces to - 7/4 (or - 1 3/4 for graphing purposes).
It will appear on the graph of this equation because this is where the line crosses the x axis.