Answer: The equation is 5x = 125
Explanation:
A pentagon is a five sided figure so all the side lengths must be equal. And to find the perimeter of a pentagon the you will the five equal side lengths.
So assume we don't know the side lengths so we will represent it by x and the side lengths are 5 so we will have five x's and they will add up to 125 and that could be represent by the equation.
x + x + x + x + x = 125
5x = 125
x = 25