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Andrea can only buy 1 snack

Okay so since she had 18 dollars at first write it down. So now,you would write down $18 and then Andrea spent $6.50 on a notebook. write that down as well. so now you do  $18 - $6.50. that equals $11.50. but Andrea needs to save $5.75. so, subtract that from the $11.50 that you wrote $6.50. write $18-$6.50=$11.50 okay so now that you have that $11.50 written down, subtract 5.75 (for Andrea's savings) and then $11.50 - $5.75 = $5.75.  So she can only buy 1 snack.