An empty fuel tank with a capacity of 208 gallons was filled partially with fuel A and then to capacity with fuel B. Fuel A contains 12% ethanol by volume and fuel B contains 16% ethanol by volume. If the full fuel tank contains 30 gallons of ethanol, how many gallons of fuel A were added?
Choose the correct choice from the following answers:
A) 160 B) 150 C) 82 D) 80 E) 50
Say there are A gallons of fuel A in the tank, then there would be 208-A gallons of fuel B.   The amount of ethanol in A gallons of fuel A is 0.12A;   The amount of ethanol in 208-A gallons of fuel B is 0.16(208-A);   Since the total amount of ethanol is 30 gallons then 0.12A+0.16(208-A)=30 --&gt; A=82.   Answer: 82.
<result>C</result>
An empty fuel tank with a capacity of 208 gallons was filled partially with fuel A and then to capacity with fuel B. Fuel A contains 12% ethanol by volume and fuel B contains 16% ethanol by volume. If the full fuel tank contains 30 gallons of ethanol, how many gallons of fuel A were added?