A car traveling at a certain constant speed takes 5 seconds longer to travel 1 km than it would take to travel 1 km at 75 km/hour. At what speed, in km/hr, is the car traveling?
Answers.
A) 70	B) 72	C) 74	D) 75	E) 78

Rationale: "time to cover 1 kilometer at 80 kilometers per hour is 1 / 75 hours = 3,600 / 75 seconds = 48 seconds ; time to cover 1 kilometer at regular speed is 48 + 5 = 53 seconds = 53 / 3,600 hours = 1 / 70 hours ; so , we get that to cover 1 kilometer 1 / 70 hours is needed - - > regular speed 70 kilometers per hour ( rate is a reciprocal of time or rate = distance / time ) . answer : a"
Answer: A