A train is moving at 4/5 of its usual speed. The train is 30 minutes too late. What is the usual time (in hours) for the train to complete the journey?
Choose the correct choice from the following answers
A) 1
B) 1.5
C) 2
D) 2.5
E) 3

Rationale: "new time = d / ( 4 v / 5 ) = 5 / 4 * usual time 30 minutes represents 1 / 4 of the usual time . the usual time is 2 hours . the answer is c ."
Answer: C