If the price of petrol increases by 25, by how much must a user cut down his consumption so that his expenditure on petrol remains constant? Choose the correct choice from the following options.
A) 25 %
B) 20 %
C) 16.67 %
D) 33.33 %
E) none of these

Rationale: "explanation : let us assume before increase the petrol will be rs . 100 . after increase it will be rs ( 100 + 25 ) i . e 125 . now , his consumption should be reduced to : - = 125 − 100125 ∗ 100 . hence , the consumption should be reduced to 20 % . answer : b"
Answer: B