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: an automobile parts supplier charges $ 25 per package of gaskets. when a customer orders more than 10 packages of gaskets, the supplier charges 4 / 5 the price for each package in excess of 10. during a certain week, the supplier sold 60 packages of gaskets. if 15 percent of the gaskets went to company x, 15 percent to company y, and the rest to company z, what was the total amount, in dollars, that the parts supplier received in payment for the gaskets ?
Options: a. 1340, b. 1445, c. 1375, d. 1415, e. 1455
a

Problem: a 340 - liter solution of kola is made from 88 % water, 5 % concentrated kola and the rest is made from sugar. if 3.2 liters of sugar, 10 liter of water and 6.8 liters of concentrated kola were added to the solution, what percent of the solution is made from sugar ?
Options: a. 6 %., b. 7.5 %., c. 9.2 %., d. 10.5 %., e. 11 %.
b

Problem: a certain sum is invested at simple interest at 18 % p. a. for two years instead of investing at 12 % p. a. for the same time period. therefore the interest received is more by rs. 480. find the sum ?
Options: a. 7000, b. 7029, c. 4000, d. 2800, e. 2791

c