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: In a box, there are 8 red, 7 blue and 6 green balls. One ball is picked up randomly. What is the probability that it is neither red nor green?

 Option A: 1/3

 Option B: 2/5

 Option C: 3/7

 Option D: 8/27

 Option E: 9/29
answer:
Option A


question:
Question: A man can do a piece of work in 5 days, but with the help of his son he can do it in 3 days. In what time can the son do it alone ?

 Option A: 13/2

 Option B: 19/2

 Option C: 21/2

 Option D: 15/2

 Option E: None
answer:
Option C


question:
Question: If a boat is rowed downstream for 600 km in 20 hours and upstream for 48 km in 4 hours, what is the speed of the boat and the river?

 Option A: 21 , 21

 Option B: 9 , 21

 Option C: 21 , 9

 Option D: 9 , 9

 Option E: 20 , 8
answer:

Option C