instruction:
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:
Question: A and B complete a work in 6 days. A can alone can do it in 10 days. If both can together can do the work in how many days?

 Option A: 7

 Option B: 3.75

 Option C: 2

 Option D: 1

 Option E: 8
answer:
Option B


question:
Question: On his first 3 tests, Rajeev received an average score of X points. If on his fourth test, he exceeds his previous average score by 24 points, what is his average score for his first 4 tests?

 Option A: X

 Option B: X+6

 Option C: X+4

 Option D: X+3

 Option E: X+2
answer:
Option B


question:
Question: A train covers a distance of 12 km in 10 minutes. If it takes 6 seconds to pass a telegraph post, then the length of the train is

 Option A: 100m

 Option B: 120m

 Option C: 140m

 Option D: 160m

 Option E: 170cm
answer:

Option B