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: A man’s speed with the current is 18 km/hr and the speed of the current is 2.5 km/hr. the man’s speed against the current is :

 Option A: 8.5 km/hr

 Option B: 9.5 km/hr

 Option C: 13 km/hr

 Option D: 12.5 km/hr

 Option E: None of these
Option C

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: What is the average of xx, 2x2x, and 66?

 Option A: 2x+2

 Option B: x+2x

 Option C: x+2x+2

 Option D: x+2

 Option E: x

Option C