There has been successive increases of 25% and then 15% in the price of gas from the previous month. By what percentage should a driver reduce gas consumption so that the expenditure does not change? Choose the correct choice from the following choices:
A) 30% B) 50% C) 66.66% D) 15% E) 75%
Let P be the original price per unit of gas.   Let x be the original gas consumption.   Let y be the reduced gas consumption.   y*1.15*1.25*P = x*P   y = x / (1.15*1.25) which is about 0.7x which is a decrease of about 30%.   The answer is 30%.
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There has been successive increases of 25% and then 15% in the price of gas from the previous month. By what percentage should a driver reduce gas consumption so that the expenditure does not change?