GMAT Flashcards

The office of 120 is split between male and female
employees at the ratio of 3:5. If 40% of the
employees are married and 20 of the married
employees in the office are men, how many of the
women working in the office are single?

In your matrix you drew, where are you getting 45 and 75? It just seems like you are pulling them out of thin air.

Note: Above question was posted by RyanP, though I have the same question.

Answer provided was:

the ratio is 3:5, so that means if you divide 120 by (3+5), you will get 15.
Now multiply 3 by 15 and 5 by 15 and you get those numbers (yes, out of thin air though with the help of some math)

Can someone please explain the reason why you can do 120 / by (3+5)? Also any alternative solution to this type of question without drawing a matrix? Thanks!