Joe's mother gave him $56 to go to the store. Joe bought 7 notebooks and 2 books. Each notebook costs $4 and each book costs $7. How much money does Joe have left? Think carefully first, then make a decision:
7 notebooks cost 7 notebooks x $4 / notebook = $28. 2 books cost 2 books x $7 / book = $14. In total Joe has spent $28 + $14 = $42. He has $56 - $42 = $14 left. So, the answer is 14.