There are 12/2 = <<12/2=6>>6 birds left.
There are 9-3= <<9-3=6>>6 puppies left.
There are 15 - 7 = <<15-7=8>>8 spiders left.
The pet store owner has 5+6 + 6 + 8 = <<5+6+6+8=25>>25 animals left
#### 25