Answer: 30
Explanation:
1. You find the slope by picking 2 points and dividing the change in the y-axis by the change in the x-axis. (Time is ALWAYS x)
(50-40)/40-20
(10)/20)
1/2
SLOPE=1/2
2. You find the y-intercept by picking a point, and plugging them into your equation, and solving for b.
(I will be using the point (20,40) )
40=1/2(20)+b
40=10+b
b=30
Y-INTERCEPT=30