Question 262531
Perimeter can be expressed as
{{{P = 2W + 2L}}}
in our case we can say
{{{26 = 2L + 2W}}}
or divide by 2 to get
{{{13 = L + W}}}
and solving for L, we get
 {{{L = 13-W}}}
----
A = LW
so by substitution, we get
A = (13-W)W
let W = x, then
{{{A(x) = x(13-x)}}}