instruction:
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.
question:
Problem: the overall age of x and y is 19 year greater than the overall age of y and z. z is how many decades younger that x ?
Options: a. 11, b. 15, c. 12, d. 19, e. 20
answer:
d

question:
Problem: the average runs scored by a batsman in 30 matches is 50. in the next 15 matches the batsman scored an average of 26 runs. find his average in all the 45 matches ?
Options: a. 31, b. 42, c. 29, d. 97, e. 27
answer:
b

question:
Problem: a man is standing on a railway bridge which is 180 m long. he finds that a train crosses the bridge in 20 seconds but himself in 8 seconds. find the length of the train and its speed
Options: a. 50 km, b. 52 km, c. 54 km, d. 56 km, e. 58 km
answer:
c