Question

Mrs. Santos is buying binders for the students in her class. She determined that 15 binders would cost $22.50.

Cost of Binders
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If all of the binders cost the same amount, which statement is true?
It will cost $12 for 18 binders.
It will cost $20 for 30 binders.
It will cost $42 for 28 binders.
It will cost $48 for 48 binders