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 certain sum earns simple interest of Rs. 800 in 2 years at a certain rate of interest. If the same sum earns compound interest of Rs.900in the same period of 2 years, What must be the rate of interest?

 Option A: 25%

 Option B: 10%

 Option C: 15%

 Option D: 20%

 Option E: 30%
answer:
Option A


question:
Question: X is able to do a piece of work in 8 days and Y can do the same work in 12 days. If they can work together for 3 days, what is the fraction of work left?

 Option A: 8/5

 Option B: 6/5

 Option C: 7/5

 Option D: 3/5

 Option E: 4/5
answer:
Option D


question:
Question: An article is bought for Rs.875 and sold for Rs.900, find the gain percent?

 Option A: 73 1/3%

 Option B: 63 1/3%

 Option C: 33 1/3%

 Option D: 2.8%

 Option E: 56.5%
answer:

Option D