Respuesta :

musiclover10045

perimeter = s+s+s

 so 7x-2 = (3x-9) + (x+7) + ?


3x-9 + x+7 = 4x-2

7x-2 - 4x-2 = 3x


remaining side is 3x
 unknown side = 7x-2 - (3x - 9 + x + 7)
 unknown side = 7x - 2 -3x + 9 -x - 7
 unknown side = = 3x 

answer

 unknown side = 3x