When the price of an item was reduced by 20%, its sale increased by x%. If there is an increase of 25% in receipt of the revenue, then the value of x is:
(a) 55.35
(b) 57.75
(c) 56.25
(d) 54.35
{Previously asked in SSC CGL Mains 2020}

Ans: (c) 56.25

Explanation:

price \times sell = revenue

In this problem we could apply ab method.

(-20, x) \rightarrow 25

\Rightarrow – 20 + x – \displaystyle\frac{20\text{x}}{100} = 25

\Rightarrow x – \displaystyle\frac{\text{x}}{5} = 25 + 20

\Rightarrow \displaystyle\frac{4}{5}\text{x} = 45

\Rightarrow x = \displaystyle\frac{225}{4} = 56.25