If the price of petrol increases by 40, by how much must a user cut down his consumption so that his expenditure on petrol remains constant?
Choices:
A) 25%
B) 20%
C) 16.67%
D) 28.6%
E) None of these
Explanation :   let us assume before increase the petrol will be Rs. 100.   After increase it will be Rs (100+40) i.e 140.   Now, his consumption should be reduced to :-   =(140−100)/140 ∗ 100.   Hence, the consumption should be reduced to 28.6%.   Answer : 28.6%
<result>D</result>
If the price of petrol increases by 40, by how much must a user cut down his consumption so that his expenditure on petrol remains constant?