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: Pipe A can fill a tank in 16 minutes and pipe B cam empty it in 24 minutes. If both the pipes are opened together after how many minutes should pipe B be closed, so that the tank is filled in 30 minutes?

Option A: 20

Option B: 16

Option C: 24

Option D: 28

Option E: 21
answer:
Option E

question:
Question: A started a business with an investment of Rs. 70000 and after 3 months B joined him investing Rs. 120000. If the profit at the end of a year is Rs. 43000, then the share of B is?

Option A: 33888

Option B: 36000

Option C: 27778

Option D: 27772

Option E: 81122
answer:
Option B

question:
Question: A school currently maintains a fixed number of students per class. If the ratio of students per class were to be increased by 1, 10 fewer classes would be run for a total of 120 students. What is the current ratio W of students per class?

Option A: W=3

Option B: 4

Option C: 6

Option D: 8

Option E: 12
answer:
Option A