Respuesta :

sammyan07

Answer:

15

Step-by-step explanation:

Substitute the values of the lengths and base in the formula for the perimeter

Perimeter = 2 (L) + b

121 = 2 (4x - 7) + x

121 = 8x - 14 + x

121 = 9x -14

121 + 14 = 9x

135 = 9x

x = 15