Subject: mathqa
Question: two mechanics were working on your car . one can complete the given job in six hours , but the new guy takes 10 hours . they worked together for the first two hours , but then the first guy left to help another mechanic on a different job . how long will it take the new guy to finish your car ?
Option: 
A: 4 / 3
B: 56 / 15
C: 17 / 5
D: 15 / 4
Answer: B