The income of a broker remains uncharged though the rate of commission is increased from 4 % to 5 % the percentage of a slump in business is_______?

A. 8 %
B. 1 %
C. 20 %
D. 80 %
Explanation:
Let the business value changes from x to y.
Then 4 % of x = 5 % of y of 4/100 × x = 5/100 × y
or y = 4/5 x.
Change in business = (x – 4/5 x) = 4/5 x.
Percentage slump in business
= (1/5 x ×1/x × 100)% = 20%