Answers:
The equation is 7n = 8.61
The cost of each binder is $1.23
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Work Shown:
n = cost of one binder in dollars
7n = cost of 7 binders in dollars
7n = 8.61 is the equation
7n/7 = 8.61/7 ... divide both sides by 7
n = 1.23 is the cost of each binder