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.

[EX Q]: Problem: a bag contains 10 green and 8 white balls. if two balls are drawn simultaneously, the probability that both are of the same colour is
Options: a. 8 / 15, b. 21 / 44, c. 3 / 5, d. 11 / 15, e. 7 / 15
[EX A]: b

[EX Q]: Problem: he average of 10 numbers is 23. if each number is increased by 4, what will the new average be ?
Options: a. 26, b. 27, c. 88, d. 99, e. 12
[EX A]: b

[EX Q]: Problem: if 20 % of x is 15 less than 15 % of 1500, then x is ?
Options: a. 872, b. 738, c. 837, d. 840, e. 1050
[EX A]:
e