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: a trader mixes 80 kg of tea at 15 per kg with 20 kg of tea at cost price of 20 per kg. in order to earn a profit of 25 %, what should be the sale price of the mixed tea ?
Options: a. 23.75, b. 22, c. 20, d. 19.20, e. none of these

A: c
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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
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Q: Problem: find the minimum value of 5 cosa + 12 sina + 12
Options: a. - 1, b. 1, c. 2, d. 3, e. none of these

A:
a
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