what is the value of X?

Question

A square and an equilateral triangle are pictured below. If the perimeter of the square is double of the perimeter of the triangle, What is the value of x?

(5x + 3) for the square

(7x - 1) for the triangle

Answer 1

If each side of the square is 5x+3 and each side of the triangle is 7x-1, then from the description:

4(5x+3) = 2(3(7x-1))

20x+12 = 42x-6

22x = 18

x = 18/22 = 9/11