Question 1071205
Let:

w = the width of the pen
l = the length of the pen

The width is 2 feet shorter than the width, so this gives:
{{{w = l - 2}}}

The area A of a rectangle is:

{{{A = l*w}}}

Substituting in w, we get:

{{{A = (l-2)*l}}}

The area A also equals 60. So, we get:


{{{60 = (l-2)*l}}}

Distribute l:

{{{60 = l^2 - 2l}}}

Bring the 60 over and we get:

{{{ 0 = l^2 - 2l - 60}}}

Using the quadratic formula, 

*[invoke solve_quadratic_equation 1, -2, -60]

(Note: l is and ugly number!)

Only the positive answer makes sense, 8.8102...

To find w, subtract 2 from l.