The length of a rectangle is 3cm longer than its width. If the perimeter of the rectangle is 54cm, find its length in cm.

length = 15 cm

Width = 12 cm

Step-by-step explanation:

Let width = w cm

Length = w + 3

Perimeter of rectangle = 54 cm

2 * (length + width) = 54

2 * (w+3 + w) = 54   {Add like terms}

2 *(2w + 3) = 54

2*2w + 2 * 3 = 54

4w + 6   = 54

Subtract 6 form both sides

4w = 54 - 6

4w = 48

Divide both sides by 4

w = 48/4

w = 12 cm

Length = 12 + 3= 15 cm