The perimeter of a rectangle is given by:
[tex]P_r = 2(l+w)[/tex]
We need to solve for length (l):
[tex]P_r = 2l+ 2w[/tex]
[tex]l = \frac{P_r - 2w}{2} [/tex]
Plug in given information:
[tex]l = \frac{68-2(10)}{2} [/tex]
[tex]l = 24[/tex]
So, the length of the rectangle is 24 inches.