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: 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
Option D

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
Option C

Question: If the average of seven numbers is 35. If one is included. The average become 40. The included number is:

 Option A: 70

 Option B: 75

 Option C: 76

 Option D: 78

 Option E: 79

Option B