The ratio of dogs to cats at an animal shelter is 33 to 22. how many dogs are at the shelter if there is a total of 3030 animals?

D : c = 33 : 22
where d is the number of dogs and c is the number of cats;
and: d + c = 3030
33 c = 22 d  / : 11
3 c = 2 d
From the other equation: c = 3030 - d
3 * ( 3030 - d ) = 2 d
9090 - 3 d = 2 d
5 d = 9090
d = 9090 : 5
d = 1818
There are 1818 dogs in the shelter.