Yesterday, the newly opened animal shelter received their first 60 animals. They got 20 more cats than dogs. How many cats did they take in? Let's answer step by step:
Let c be the number of cats and let d be the number of dogs. We know that c = 20 + d and that the total number of animals is c + d = 60. Replacing c gives 20 + d + d = 60 animals. Combining like terms and subtracting 20 from both sides, we get 2d = 40. Dividing both sides by 2, we get d = 40 / 2 = 20. The shelter therefore received 20 + 20 = 40 cats. The answer: 40.