Sam and Nik start from A and B respectively at the same time and travel towards each other at constant speeds along the same route. Sam meets Nik at point C on the road which is 600m away from starting point A and 400m away from point B. The speed of Sam is 50 m/m(meter/minute). How much time did Sam take to cover the distance between A and B?  Select
A) 10 minutes	B) 15 minutes	C) 20 minutes	D) 22 minutes	E) 17 minutes

Rationale: total distance from a to b - a - c = 600 m , b - c = 400 m ; therefore a - b = 1000 m ; vs = 50 m / m ; therefore , t = 1000 / 50 = 20 minutes . option c
Answer: C