Q: A train 640 m in length crosses a telegraph post in 16 seconds. The speed of the train is?
Options:
(A) 22 kmph
(B) 77 kmph
(C) 144 kmph
(D) 71 kmph
(E) 88 kmph
A: (C)
Explain how we arrive at this answer:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Explanation: S = 640/16 * 18/5 = 144 kmph