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.

Problem: a sells a bicycle to b and makes a profit of 50 %. b sells the same bicycle to c at a profit of 25 %. if the final s. p. of the bicycle was rs. 225, find out the cost price of the bicycle for a.
Options: a. 237, b. 126, c. 971, d. 611, e. 120
e

Problem: the area of a triangle is with base 18 m and height 6 m ?
Options: a. 88 m 2, b. 10 m 2, c. 66 m 2, d. 54 m 2, e. 31 m 2
d

Problem: if the cost price of 18 articles is equal to the selling price of 16 articles, what is the percentage of profit or loss that the merchant makes ?
Options: a. 20 % loss, b. 12.5 % profit, c. 33.33 % loss, d. 30.33 % loss, e. none of these

b