Perimeter of a rectangle = (2x length) + ( 2 x width)
if the length is 3 more than twice the width then
length = 3 +( 2x width)
substituting for the perimeter which is given as 54 inches and the length derived as above in to the equation for the perimeter. we have
54 = 2(3+(2 x w)) + 2w
54 = 6 +4w +2w
54 =6 +6w
6w = 48
6w/6 = 48/6
w = 8 inches
Substituting for w in the equation for length gives us
length = 3 + (2 x8)
L= 3+16
L = 18 inches
The dimesnsions of the rectangle are therefore
W = 8 inches
and
L = 18 inches