Question 47587
The time it took to decrease the electricity cost is one year.
(12000,0) and (10920,1)
Now, find slope:
M = (y2 - y1)/(x2 - x1) = (12000 - 10920)/(0 - 1) = -1080
1080/12000 = 0.09 = 9%
The Rate of Decrease: 9%
Check: 9% of 12000 is 1080 .... 12000 - 1080 = 10920