Question 494347
Given
Length = l =W + 3
Perimeter = 24
Width = W = ?

Perimeter of a rectangle = 2 length + 2 width
P = 2*l + 2*w
24=2*(w+3)+ 2w
24=2w+6+2w
24-6=4w
18=4w
w=18/4
w=9/2
w=4.5

l=w+3
put the value of w in above equation
l=4.5+3
l=7.5

Dimensions of rectangle

length = 7.5cm, width=4.5cm, Perimeter=24cm, 
Area of rectangle =w*l=7.5*4.5=33.75cm^2