There has been successive increases of 20% and then 10% 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?	Options:
A) 16%
B) 20%
C) 24%
D) 28%
E) 32%
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*1.1*1.2*P = x*P   y = x / (1.1*1.2) which is about 0.76x which is a decrease of about 24%.   The answer is 24%.
<result>C</result>
There has been successive increases of 20% and then 10% 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?