Length = L
Width = W
The difference between the length and width of a rectangle is 7cm
L - W = 7 cm
Perimeter = 22cm
Perimeter = 2L+2w
SO:
L-W = 7 (a)
2L+2W=22 (b)
Solve (a) for L
L= 7+w
Replace L on (b)
2(7+W)+2w=22
Solve for W
14+2W+2W =22
14+4w =22
4w= 22-14
4w = 8
W = 8/4
W= 2
Replace W on (a)
L-2 = 7
Solve for L
L= 7+2
L=9
Width = 2cm
Length =9 cm
