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: The average runs scored by a batsman in 20 matches is 40. In the next 10 matches the batsman scored an average of 20 runs. Find his average in all the 30 matches?

 Option A: 31

 Option B: 46

 Option C: 88

 Option D: 33.33

 Option E: 12
[EX A]: Option D

[EX Q]: Question: A man can row a boat at 20 kmph in still water. If the speed of the stream is 6 kmph, what is the time taken to row a distance of 66 km downstream?

 Option A: 30/83 hours

 Option B: 33/13 hours

 Option C: 31/13 hours

 Option D: 30/13 hours

 Option E: 30/14 hours
[EX A]: Option B

[EX Q]: Question: A collection of books went on sale, and 2/3 of them were sold for $2.25 each. If none of the 40 remaining books were sold, what was the total amount received for the books that were sold?

 Option A: $160

 Option B: $150

 Option C: $280

 Option D: $200

 Option E: $180
[EX A]:
Option E