GMAT Quantitative Reasoning Practice Test 2

Since John spent all of the $135 on the tickets, their prices must sum up to $135. The Minimum amount spent for the $12 tickets, is the smallest amount that is divisible by 12 , and still leaves an amount divisible by 5 . $60 is the smallest amount both divisible by 12 and leaving $135−$60=$75, which is divisible by $5.