Question

Jared wrote an equation for the perimeter of an equilateral triangle as 3x = 20. What does x represent in his equation?

Answer 1

The perimeter of an object is equal to its sides added up.  Because this is a triangle, it will have 3 equal sides.  Since the triangle has 3 equal sides, its perimeter will be equal to one of its side lengths * 3.  

Because the perimeter will be equal to one of its side lengths * 3, x is equal to one of the triangle's side lengths.

Answer 2

X is the variable for the length of the sides.

Because a equalilateral ∆ has 3 equal sides, they can be represented by one term (x)