Jean stocked her aquarium with 36 fresh-water fish , which cost $212 . The male fish cost $5 each, while the female fish cost $7 each . Find the number of male fish and the number of female fish ?

Question

I need help with the math because I don’t understand stand the lesson I don’t get how it is explained either

Answer 1

Hey, Angela.

This is a system of two equations.

We're going to assume that all fish are either male or female, with M representing the male fish and F representing the female fish.

So M + F = 36.

And because the males cost $5 and the female fish cost $7, we also have

5M + 7F = 212.

This question is set up really nicely for substitution or for elimination, so if you prefer one over the other, use that one.

I'm going to do substitution, though.

If M + F = 36, then M = 36 - F

And we'll substitute that into the second equation

5(36 - F) + 7F = 212

Distribute, then solve for F.

Once you have F, plug it back into M+F = 36 to find M.

You can shoot me a message if you need further help, or if you want me to walk you through the elimination method for this question.