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: 10 ^ ( 600 ) ã · 10 ^ ( 580 ) = ?
Options: a. 10 ^ 10, b. 10 ^ 20, c. 10 ^ 22, d. 10 ^ 23, e. 10 ^ 24
[A]: b


[Q]: Problem: rajani has to read a book of 445 pages. she has already read the first 157 pages of the book and if she reads 24 pages of the book everyday then how long will she take now to complete the book ?
Options: a. 25 days, b. 20 days, c. 46 days, d. 21 days, e. none of these
[A]: e


[Q]: Problem: in a university the average age in an arts class is 21 and average age in technical class is 18. what is the age average of university if there are 8 arts classes and 5 technical classes ?
Options: a. 18.75, b. 19.85, c. 20.32, d. 20.9, e. 21.0
[A]:
b