sean has $86 to spend. he can spend all of it on one cd and two dvd's, or he can buy two cd's and one dvd and have $16 left over. what is the price of a cd? of a dvd?
Let c = cd and d = dvd
c + 2d = 86
2c + d = 86-16
Use whatever method you want to solve these equations, elimination or substitution.