Subject: mathqa
Question: a certain car traveled twice as many miles from town a to town b as it did from town b to town c . from town a to town b , the car averaged 10 miles per gallon , and from town b to town c , the car averaged 18 miles per gallon . what is the average miles per gallon that the car achieved on its trip from town a through town b to town c ?
Option: 
A: 13
B: 13.5
C: 14.5
D: 14
Answer: C