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.
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Question: Question: If x is positive and y is negative, which of the following must be true?

 Option A: The product of x and y is positive

 Option B: The sum of x and y is positive

 Option C: The sum of x and y is negative

 Option D: The difference of x and y is positive

 Option E: The sum of x^2 and y^2 is positive

Answer: Option E


Question: Question: One-tenth of the students at a nursery school are 4 years old or older. If 20 students have not yet reached their third birthday, and a total of 50 students are not between 3 years old and 4 years old, how many children are in the nursery school?

 Option A: 150

 Option B: 300

 Option C: 450

 Option D: 490

 Option E: 620

Answer: Option B


Question: Question: The price of raw materials has gone up by 15%, labour cost has also increased from 25% of the cost of raw material to 30% of the cost of raw material. By how much percentage should there be reduction in the usage of raw materials so as to keep the cost same?

 Option A: 28%

 Option B: 17%

 Option C: 27%

 Option D: 24%

 Option E: Cannot determined

Answer:
Option B