Question

That bad triangle

Answer 1

you need to set up systems

Answer 2

let x be the length of a side in the square



the perimeter of the triangle is P = 3x - 9

since the perimeter of the square is 4x

and the the square is 30 inches longer than the triangle

4x = 3x - 9 + 30

give x = 21

The square has side length 21 inches