Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

[Q]: Problem: the average runs scored by a batsman in 20 matches is 40. in the next 10 matches the batsman scored an average of 30 runs. find his average in all the 30 matches ?
Options: a. 31, b. 36.67, c. 88, d. 13, e. 12
[A]: b


[Q]: Problem: two trains of equal are running on parallel lines in the same direction at 45 km / hr and 36 km / hr. the faster train passes the slower train in 36 sec. the length of each train is ?
Options: a. 45, b. 88, c. 66, d. 55, e. 22
[A]: a


[Q]: Problem: ifaequals the sum of the even integers from 2 to 120, inclusive, andbequals the sum of the odd integers from 1 to 119, inclusive, what is the value of a - b ?
Options: a. 60, b. 10, c. 19, d. 20, e. 21
[A]:
a