Question 939572
let length be x in
width  =  x-8
area  = 20 in^2
formula: area = length x width
         20 = x*(x-8)
      20 = x*x-x*8
       {{{20 = x^2-8x}}}
           move 20 to the right
 {{{ 0=x^2-8x-20 }}}
 *[invoke quadratic "x", 1, -8, -20 ]
 but x cannot be negative .
it should be positive value
  x=10
 length  = 10 in
 width  = 10-8 = 2 inches
Result: length  = 10 in
  width  = 2 in