The task is to generate the correct answer for a given math problem.

[Q]: Problem: tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random . what is the probability taht the ticket drawn has a number which is a multiple of 3 or 5 ?
[A]: 9 / 20

[Q]: Problem: a train running at the speed of 72 km / hr crosses a pole in 9 seconds . find the length of the train .
[A]: 180 meter

[Q]: Problem: the ratio of the number of females to males at a party was 1 : 2 but when 7 females and 7 males left , the ratio became 1 : 3 . how many people were at the party originally ?
[A]:
42