A person walking at 5/6th of his usual speed is 40 minutes late to his office. What is his usual travel time to his office?

A. 3 hours 20 minutes
B. 3 hours 15 minutes
C. 3 hours 30 minutes
D. 3 hours
Let his usual speed be x kmph, the distance to his office be y km and his usual travel time be t hrs. y = xt = (5/6)x * (t+(40/60)) Solving the equation,
t = 3.33 hrs = 3 hrs 20 minutes