Question 1135879
<pre>
                  time     rate      time       production
                  for       in      working     in fraction
                 1 job   jobs/min   together      of a job
--------------------------------------------------------
slower computer   55       1/55        x         (1/55)x 
faster computer   45       1/45        x         (1/45)x
--------------------------------------------------------
                               total production = 1 job  

                              (1/55)x + (1/45)x = 1

Multiply through by LCD = 495

                                       9x + 11x = 495
                                            20x = 495
                                              x = 495/20
                                              x = 99/4
                                              x = 24.75 minutes 

Edwin</pre>