You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

[EX Q]: Question: Q is as much younger than R as he is older than T. If the sum of the ages of R and T is 50 years, what is definitely the difference between R and Q's age?

 Option A: 23

 Option B: 28

 Option C: 25

 Option D: 19

 Option E: 11
[EX A]: Option C

[EX Q]: Question: A businessman earns $28800 in December, thus decreasing his average annual (January to December) earnings by $1300. His average annual earnings would be
Source: CMAT Preparation

 Option A: $29000

 Option B: $33500

 Option C: $40200

 Option D: $41000

 Option E: $43100
[EX A]: Option E

[EX Q]: Question: How many 3-digit numerals begin with a digit that represents a prime number?

 Option A: 16

 Option B: 80

 Option C: 400

 Option D: 180

 Option E: 240
[EX A]:
Option C