A pet store sells angle fish for $6 each and clown fish for $4 each. If the pet store sold fish for $36, how many of each type did they sell?

There are four possibilities ... but first does the problem tell you how many total fish were sold?

If not the possible combinations are:

0 angel and 9 clownfish

2 angel and 6 clownfish

4 angel and 3 clownfish

6 angel and 0 clownfish