The price of a Maruti car rises by 30% while the sales of the car came down by 20%. What is the percent change in the total revenue?
 - 4
 - 2
 + 4
The price becomes 1.3p from the original price p
while the sales come down to 0.8s from the original sales s.
Thus the old revenue was (p X s). While the new revenue is (1.04p X s).
Thus the % change in the revenue is [(1.04 - 1.00) ps/ps] X 100 = 4%.