There are 40 animals in the shelter, 18 of that animals are cats.
We need to find the percent of the animals that are cats.
Then, 40 animals represent 100% in the shelter.
We can use the rule of three to find the cat's percent:
Therefore:
40 animals -------------- 100%
18 cats ------------------------ x
x = (18*100)/40
x =45
So, 45 % of the animals are cats.