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 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 %.
[EX A]: b

[EX Q]: Problem: dropbox charges $ 3.10 for first 1 / 5 of a month for 500 gb storage, plus $ 0.40 for each additional 1 / 5 of a month. what would dropbox charge for a data storage of 500 gb for 8 months ?
Options: a. $ 15.60, b. $ 16.00, c. $ 17.80, d. $ 18.70, e. $ 19.10
[EX A]: d

[EX Q]: Problem: a ( 7, w ^ 3 ) is the ( x, y ) coordinate of point located on the parabola y = x ^ 2 + 15. what is the value of w ?
Options: a. 3., b. 4., c. 5., d. 6., e. 9.
[EX A]:
b