Question

Kevin is starting a saltwater aquarium with 36 fish. He wants to start with 11 times as many damselfish as clown fish

Answer 1

he would have about 3 Clownishes and 33 Damsel fishes. 
If he has 3 Clown fishes and wants to have 11 times as many Damsel fishes as he would clown fishes you'd have to multiply 3 by 11.
You get the 3 by dividing 36 by 11

Answer 2

d+c=36
11 times as many d as c
d=11c
sub

11c+c=36
12c=36
divide both sides by 12
c=3
sub

d=11c
d=11(3)
d=33


33damselfish
3 clownfish