Two-thirds of all the animals on my street are cats and the rest are dogs.  If there are 300 animals on the street, what's the total number of legs of dogs that are on the street?
The number of cats on the street is 2/3*300 = <<2/3*300=200>>200
If there are 300 animals on the street, and 200 are cats, there are 300-200 = <<300-200=100>>100 dogs.
Since a dog has four legs, the total number of legs the 100 dogs have is 100*4 = <<100*4=400>>400 legs.
#### 400