Ethan sells e candy bars for $2.50 apiece and Chloe sells c candy bars for $2.00 apiece to raise
money for a school trip. Ethan sold 15 fewer candy bars than Chloe, but he also got a $6.00
donation. If Chloe and Ethan raised the same amount of money, which of the following systems
could be used to find how many candy bars each sold?