Can You Set Up An Equation For The Perimeter Involving Only L, The Length Of The Rectangle?

Perimeter of rectangle = 2(length + width)

Let Length = L
So Width = L-2
perimeter = p = 80
Putting the values in the equation you will get

P=2(L+W)
P=2(L+(L-2)) >> this is the equation for the perimeter involving only L

80=2(L+L-2)
80=2(2L-2)
80=2(2L-2)
Dividing both sides by 2 you will get
80/2=2(2L-2)/2
40 = 2L-2
40+2 = 2L
2L=42
Again divide both sides by 2 you will get
2L/2 = 42/2
L = 21
So length =21
Width = L-2 = 21-2 = 19

So length = 21 and Width =19.