A company decreased the price of its main product by 20%. Subsequently, the number of units sold increased such that the total revenue remained unchanged. What was the ratio of the percent increase in the units sold to the percent decrease of the original price for this product?
Pick:
A) 3.0
B) 7.0
C) 5.0
D) 2.0
E) 1.0

Rationale: "for the total revenue to remain the same when the price is one fifth , the number of products sold must five times . therefore increase in the number of products sold is 100 % = > the required ratio = 100 % / 20 % = 5.0 answer : c"
Answer: C