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.
1a because it is going through the origin. if the line is going straight through the origin then it is automatically proportional. hope this helps in the future