Question

I have no idea what this means, it’s confusing me

Answer 1

Explanation:

the perimeter, it is the sum of all sides.

an expression is a combination of terms that together represent a certain thing, meaning.

and "simplified" means to combine as many terms as possible, so that the expression becomes as simple and short as possible.

so,

6y + (y - 4) + 3y + 5 = 10y + 1

that's it.