The perimeter of a square is equal to the perimeter of an equilateral triangle. The length of a side of the square is given by x, and the length of a side of the equilateral triangle is given by x 1. Which equation can be used to find the value of x? x = 3 (x 1) 3 x = 4 (x 1) 4 x = 3 (x 1) x = x 1.