Consider that the perimeter of a rectangular figure is given by:
P = 2w + 2l
where l is the length and w is the width.
l = 20 in
w = ?
P = 60 in
By replacing the previous values into the formula for P and by solving for w, you get:
60 = 2w + 2(20)
60 = 2w + 40
60 - 40 = 2w
20 = 2w
20/2 = w
10 = w
HENCE, THE WIDTH OF THE RECTANGULAR ROOF SHINGLE IS 10 in
