Answer:
39 cm
Step-by-step explanation:
The perimeter of a rectangle is given as 2 (w + l) or 2w + 2l, where w and l are the sides.
Let us use w as 3 cm.
The perimeter of the rectangle is 2(3) + 2l = 6 + 2l
6 + 2l = 84 cm
We move the 6 to the left hand side and it goes from positive to negative.
2l = 84 - 6cm
2l = 78 cm
Divide both sides by 2.
l = 39 cm
There you have the answer for side l.
Hope this helps.
