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: A lady bought five books namely A,B,C,D,E to distribute her 7 friends. How many ways she can distribute books?

 Option A: 7^3

 Option B: 7^4

 Option C: 7^5

 Option D: 7^6

 Option E: 7^2
[EX A]: Option C

[EX Q]: Question: X is able to do a piece of work in 8 days and Y can do the same work in 12 days. If they can work together for 3 days, what is the fraction of work left?

 Option A: 8/5

 Option B: 6/5

 Option C: 7/5

 Option D: 3/5

 Option E: 4/5
[EX A]: Option D

[EX Q]: Question: The ratio of the earnings of P and Q is 9:10. If the earnings of P increases by one-fourth and the earnings of Q decreases by one-fourth, then find the new ratio of their earnings?

 Option A: 4/7

 Option B: 3/2

 Option C: 3/5

 Option D: 9/4

 Option E: 3/1
[EX A]:
Option B