A sum of money is sufficient to pay X's wages for 36 days and Y's wages for 45 days. The same money is sufficient to pay the wages of both for?
Select:
A) 16  B) 17  C) 18  D) 19  E) 20

Rationale: let the total money be $ x x ' s 1 day work = $ x / 36 y ' s 1 day work = $ x / 45 x + y 1 day work = $ x / 20 money is sufficient to pay the wages of both for 20 days answer is e
Answer: E