You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

Question: A train passes a station platform in 36 sec and a man standing on the platform in 20 sec. If the speed of the train is 54 km/hr. What is the length of the platform?

 Option A: 229

 Option B: 240

 Option C: 288

 Option D: 277

 Option E: 221
Option B

Question: At a local supermarket, a box of cereal usually costs 22 dollars. This week, the supermarket sells the box of cereal for 11 dollars. How much money will you save if you buy this cereal at this supermarket?

 Option A: 11 dollars

 Option B: 13 dollars

 Option C: 14 dollars

 Option D: 12 dollars

 Option E: 10 dollar
Option A

Question: Three number are in the ratio of 3 : 4 : 5 and their L.C.M. is 2400. Their H.C.F. is:

 Option A: 40

 Option B: 80

 Option C: 90

 Option D: 100

 Option E: 120

Option A