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: In a class of 40 students, 10 did not opt for math. 15 did not opt for science and 2 did not opt for either. How many students of the class opted for both math and science?

 Option A: 13

 Option B: 15

 Option C: 7

 Option D: 17

 Option E: 18
[A]: Option C


[Q]: Question: How much time does a train 150 metres long running at 90 km/hr take to pass a pole?

 Option A: 7.9s

 Option B: 6s

 Option C: 7.5s

 Option D: 7.6s

 Option E: 7.4s
[A]: Option B


[Q]: Question: A waitress's income consists of her salary and tips.During one week ,her tips were 9/4 of her salary.What fraction of her income for the week came from tips?

 Option A: 9/13

 Option B: 1/6

 Option C: 1/3

 Option D: 4/9

 Option E: 5/9
[A]:
Option A