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: If x persons take y days to complete z similar jobs, how long does it take y persons to complete 1 such job?

 Option A: z

 Option B: x

 Option C: x/y

 Option D: z/x

 Option E: x/z
Option E

Question: The original price of a shirt was $20. It was decreased to $15 . What is the percent decrease of the price of this shirt.

 Option A: 25%

 Option B: 35%

 Option C: 45%

 Option D: 55%

 Option E: 65%
Option A

Question: The distance light travels in one year is approximately 5,870,000,000,000 miles. the distance light in 100 year is

 Option A: 587 x 10power9 miles

 Option B: 587 x 10power12 miles

 Option C: 587 x 10power8 miles

 Option D: 587 x 10power-12 miles

 Option E: 587 x 10power-9 miles

Option B