Charlie had 10 stickers. He bought 21 stickers from a store in the mall and got 23 stickers for his birthday. Then Charlie gave 9 of the stickers to his sister and used 28 to decorate a greeting card. How many stickers does Charlie have left?
The total number of stickers is 10 + 21 + 23 = <<10+21+23=54>>54.
The number of stickers given away and used on the greeting card is 9 + 28 = <<9+28=37>>37.
Charlie has 54 − 37 = 17 stickers left.
#### 17