Square and triangles

Question

The square and the equilateral triangle at the right have the same perimeter. Find the length of the sides of the triangle.

square: x+5

triangle 3x

answer: 12(?)

needed: how do I get there.

Answer 1

The perimeter of the square is represented by 4(x+5). This is because one side of the square is represented by x+5, and there are 4 sides.

The perimeter of the triangle is represented by 3(3x) because 3x represents one side of the equilateral triangle and there are 3 equal sides.

Since the perimeters are equal:

4(x+5) = 3(3x)

Solve that equation for x. That will NOT be the answer to the question. That value must be plugged into the expression for the length of the side of the triangle to get the final answer.