When the price of an item was reduced by 20%, its sales increased by x% . If there is an increase of 25% in the receipt of the revenue, then the value of x is: 

56.25%

20% =  \(\frac{1}{5}\)  &  25% =  \(\frac{1}{4}\)

Ratio of ,            Original      :       New

Price                        5          :        4

Sale                     100          :       100 + x

----------------------------------------------------------

Revenue                   4          :          5

ATQ, 

 \(\frac{5× 100   }{4 × (100+x)   }\) = \(\frac{4}{5}\)

2500 = 1600 + 16x

16x = 900

x = 56.25%