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.

[EX Q]: 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
[EX A]: Option A

[EX Q]: Question: A contractor undertakes to built a walls in 50 days. He employs 60 peoples for the same. However after 25 days he finds that only 40% of the work is complete. How many more man need to be employed to complete the work in time?

 Option A: 25

 Option B: 90

 Option C: 35

 Option D: 20

 Option E: None of these
[EX A]: Option B

[EX Q]: Question: A solution of 80 litres contains oil and water in the ratio 10:x. If five litres of water is added to the solution, the ratio becomes 20:10, find the value of x?

 Option A: 4.1

 Option B: 4.9

 Option C: 4.7

 Option D: 5.7

 Option E: 8.5
[EX A]:
Option A