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.