Respuesta :

Answer:

51*2=102. 210-102=108. 108/2=54.

The length is 54.

Answer: 54 cm

Step-by-step explanation:

Length is x

Perimeter = 2w+2l

Perimeter= 2(51)+2(x)=210

Perimeter=102+2x=210

Perimeter=2x=210-102

Perimeter=2x=108

Length= 54 cm