Answer
There are 27 cats in the animal shelter.
Work Step by Step
The ratio of cats to dogs at the animal shelter is 3 to 5. If there are 45 dogs, how many cats are there?
Let's assume the required no of cats are x.
Now, we will write the proportion for the given details
$\frac{3 cats}{5 doga} = \frac{x cats}{45 doga}$
so. $ 3\times45= 5\times x$ (Same units cancelled)
Now divide both sides by 5.
$\frac{135}{5} = \frac{5x}{5}$
$ x = 27 $
There are 27 cats in the animal shelter.