instruction:
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:
Question: A man rows his boat 85 km downstream and 45 km upstream, taking 2 1/2 hours each time. Find the speed of the stream?

 Option A: 6 kmph

 Option B: 9 kmph

 Option C: 3 kmph

 Option D: 8 kmph

 Option E: 1 kmph
answer:
Option D


question:
Question: The area of a parallelogram is 72sq m and its altitude is twice the corresponding base. Then the length of the base is?

 Option A: 6

 Option B: 9

 Option C: 7

 Option D: 62

 Option E: 2
answer:
Option A


question:
Question: P, Q and R can do a work in 20, 30 and 60 days respectively. How many days does it need to complete the work if P does the work and he is assisted by Q and R on every third day?

 Option A: 10 days

 Option B: 14 days

 Option C: 15 days

 Option D: 9 days

 Option E: 5 days
answer:

Option C