A pet store currently has a total of 45 cats and dogs. There are 7 more cats than dogs. How do you find the number of cats and dogs in the store?

1 Answer
Nov 20, 2016

In the store there are currently 19 dogs and 26 cats.

Explanation:

We are looking for the number of cats and dogs so let's call #c# the number of cats and #d# the number of dogs.

Now we are told there are 7 more cats (#c#) than dogs (#d#) so we can write this in mathematical terms as:

#c = d + 7#

We are also told there is a total of 45 cats (#c#) and dogs (#d#). So we can write this as:

#c + d = 45#

We can now substitute, from the first equation, #d + 7# for #c# in the second equation and solve for #d#:

#(d + 7) + d = 45#

#d + 7 + d = 45#

#2d + 7 = 45#

#2d + 7 - 7 = 45 - 7#

#2d = 38#

#(2d)/2 = 38/2#

#d = 19#

Now that we have #d#, or the number of dogs, we can substitute this back into the first equation to calculate #c#, or the number of cats:

#c = 19 + 7#

#c = 26#