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

Problem: what decimal fraction is 90 ml of a litre ?
. 09

Problem: what is the probability of getting a queen or spade from a set of cards ?
4 / 13

Problem: when positive integer n is divided by positive integer p , the quotient is 18 , with a remainder of 7 . when n is divided by ( p + 3 ) , the quotient is 15 and the remainder is 1 . what is the value of n ?

20