Respuesta :

Answer:

12

Step-by-step explanation:

3x + 3x + 5x - 4 + 5x - 4 = 56

16x - 8 = 56

16x = 64

x = 4

3(4) = 12

Hope this helps! Pls give brainliest!

Answer:

area= 5x(5x-4)

Step-by-step explanation:

perimiter= 2(5x-4) + 2(5x-4)