Question

How did we get C part in this problem? Aren't we suppose to subtract 2000 by 4000 and then get the dependent variable and for the independent variable -
40-20= 20 ???
How do we do this?
Please explain fully?

Answer 1

Ur points are set up like this (x,y)....so ur x axis number, then ur y axis number...so 2 of the points that are on ur line are (0,12000) and (120,0)
u do not subtract 2000 by 4000...if u wanted to use those points, they would be (80,4000) and (100,2000)

slope (rate of change) = (y2 - y1) / (x2 - x1)
(0,12000) ...x1 = 0 and y1 = 12000
 (120,0) ......x2 = 120 and y2 = 0
slope = (0 - 12,000) / (120 - 0) = -12,000/120 = -100 <== ur slope

Answer 2

To get rate of change, you find the slope. The slope = the rate of change. You take the final value for the dependent variable (y2) minus the initial value for the dependent variable ALL OVER the final value for the independent variable minus the initial value for the independent variable. That is:
(0-12,000/120-0) or -100.