The speed at which a man can row a boat in still water is 15 kmph. If he rows downstream, where the speed of current is 5 kmph, what time will he take to cover 60 metres?  Pick one: A) 16 seconds B) 76 seconds C) 10.8 seconds D) 12 seconds E) 18 seconds

Rationale: "speed of the boat downstream = 15 + 5 = 20 kmph = 20 * 5 / 18 = 50 / 9 m / s hence time taken to cover 60 m = 60 * 9 / 50 = 10.8 seconds . answer : c"
Answer: C