Question

Two sides of a triangle have the same length. The third side measures 6 m less than twice the common length. The perimeter of the triangle is 22 m. What are the lengths of the three​ sides?

Answer 1

Let x be the common length. Then, the sides of the triangle are x, x, and 2x-6. These three sides sum up to 22, so you have

$x+x+2x-6 = 22 \iff 4x = 28 \iff x = 7$

So, the two equal sides are 7m long, and the third side is

$2\cdot 7 - 6 = 14 - 6 = 8$