Question

In Sam’s pet corner, there are puppies and parrots, the total of 15 heads and 50 feet. How many parrots and how many puppies?

Answer 1

Puppies = 4 feet
Parrots = 2 feet

15 heads = 15 animals

Assumed all Parrots,
15 x 2 = 30 feet

50 - 30 = 20
There are 20 extra feet which must belong to puppies' extra 2 feet each
20 ÷ 2 = 10

There are 10 puppies
15 - 10 = 5
There are 5 parrots

Check: 
10 x 4 + 5 x 2 = 50 feet (Correct)