Final answer:
Each litter contains 4 animals.
Step-by-step explanation:
To find the number of animals in each litter, we need to use the given information. We know that the vet put 2 litters of kittens in a cage with 5 other kittens, so there are a total of 7 kittens in the first cage. In the second cage, there are 3 litters of puppies with 1 other puppy, so there are 4 puppies in the second cage. Since the cages now contain the same number of animals, we can set up an equation: 2 litters of kittens + 5 other kittens = 3 litters of puppies + 1 other puppy. Substituting the given numbers, we have 2x + 5 = 3x + 1, where x represents the number of animals in each litter. Solving this equation, we find that x = 4. Therefore, each litter contains 4 animals.