Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

Q: Problem: the perimeter of a triangle is 40 cm and the inradius of the triangle is 2.5 cm. what is the area of the triangle ?
Options: a. 87 cm 2, b. 28 cm 2, c. 98 cm 2, d. 26 cm 2, e. 50 cm 2

A: e
****
Q: Problem: if 9 / ( 1 + 4 / x ) = 1, then x =
Options: a. 3, b. 1 / 2, c. 1 / 3, d. - 1 / 3, e. - 3

A: b
****
Q: Problem: in the youth summer village there are 125 people, 50 of them are not working, 25 of them have families and 75 of them like to sing in the shower. what is the largest possible number of people in the village, which are working, that do n ' t have families and that are singing in the shower ?
Options: a. 75, b. 80, c. 85, d. 100, e. 90

A:
a
****