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Gerard has two $5 bills and three $10 bills, so he has (2 x 5)+(3 x 10) = $40 total. If he spends $3.85 for a milkshake and $7.98 for a banana split, he will have $28.17 left.
40 - 3.85 - 7.98 = $28.17.
Added 11/25/2014 11:38:02 AM
This answer has been confirmed as correct and helpful.