On Saturday, Erica saw 3 + 2 = <<3+2=5>>5 animals
On Sunday she spotted 2 + 5 = <<2+5=7>>7 animals
On Monday, she saw 5 + 3 = <<5+3=8>>8 animals
Adding up all the animals Erica saw gives a total of 5 + 7 + 8 = <<5+7+8=20>>20 animals
#### 20