binder + folders = total cost
7.25 + folders = 9.05
he bought 6 folders at x cost each
7.25 + 6x =9.05
subtract 7.25 from each side
6x = 9.05-7.25
6x= 1.80
divide each side by 6
x = .30
Each folder cost $.30 or 30 cents
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