these is my homework, and I would like for some to tell me if I did rigth.

Question

10. A rentangle has width the same as a side of a square whose perimeter is 20m. the length of the rectangel is 9 M. Find the perimeter of this rectangle.
W=L+20m

2L+w=9
2L+2w(w-18)=84
2L+2w-18=84
4L+18=84
4L=18-84
4L=66
L=66/4

Each side of the square must be 5 m (20/4).
The rectangle's measurements are 5 m x 9 m.
P = 2W + 2L
P = 10 + 18
P = ____________