There are 12 dogs and half are standing on their back legs so that means 12/2 = <<12/2=6>>6 are standing on their back legs
A dog has 2 back legs and only 6 are standing on their back legs meaning that there are 2*6 = <<2*6=12>>12 paws on the ground
The other 6 dogs are standing on all 4 legs which means these 6 dogs have 6*4 = <<6*4=24>>24 paws on the ground
When you add them together 12+24 = <<12+24=36>>36 paws on the ground
#### 36