With an average speed of 40 km/hr a car reaches its destination on time. If it goes with an average speed of 35 km/h, it is late by 15 minutes. The total journey is? Choose the correct choice:
A) 30 km
B) 40 km
C) 70 km
D) 80 km
E) 90 km

Rationale: let the total journey be x km . x / 35 - x / 40 = 15 / 60 solving for x , we get x = 70 therefore , total journey = 70 km . answer : c
Answer: C