A group of tourists spends $156 to rent snorkels and fins. A total of 15 snorkels and 18 pairs of fins are rented. Renting a snorkel costs four times as much as renting a pair of fins. How much does it cost to rent a snorkel?

You could use many methods to find the answer to this problem, but I am going to use the most efficient one I know.

18f+15 (4f) = 156

F is for fins. We should now solve the equation.

18f+60f=156

78f=156

156:78=2

So fins cost 2 dollars. Now, we know snorkels cost four times the amount of fins. Four times 2 is eight. So the snorkels cost $8 to rent. Let's check our math.

15 (8) + 18 (2)

120+36=156

So it cost $8 to rent a snorkel.