Since (5/31)/(15/23)=(5/31)*(23/15) (by finding the reciprocal and multiplying), we get 115/465. Since they are both divisible by 5, we learn that 5 goes into 115 23 times and into 465 93 times (since 465/5=93), resulting in 23/93. Since 23 is a prime number (their only factors are 23 and 1), we end there