Question: I'm stuck on this math problem: John brings his dog to the vet. His dog needs 2 vaccines, which are $20 each, and a heartworm check. The heartworm check is 60% of his total bill. If he brought $125 with him, how much does he leave with?
Can you help?
Answer: 
The vaccines cost 40 because 2 x 20 = 40
The vaccines are 40% of his total bill because 100 - 60 = 40
The total bill is $100 because 40 / .4 = 100
He leaves with $25 because 125 - 100 = 25