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.

[Q]: Question: I. a3 - 305 = 207,
II. b2 - 72 = -8 to solve both the equations to find the values of a and b?

Option A: a > b

Option B: a b

Option C: a < b

Option D: a b

Option E: a = b or the relationship between a and b cannot be established.
[A]: Option B

[Q]: Question: Two pipes A and B can separately fill a cistern in 10 and 15 minutes respectively. A person opens both the pipes together when the cistern should have been was full he finds the waste pipe open. He then closes the waste pipe and in another 4 minutes the cistern was full. In what time can the waste pipe empty the cistern when fill?

Option A: 7

Option B: 9

Option C: 5

Option D: 4

Option E: 8
[A]: Option E

[Q]: 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: 7 kmph

Option B: 5 kmph

Option C: 3 kmph

Option D: 8 kmph

Option E: 2 kmph
[A]:
Option D