Question 978601
"The orders for christmas" is one job.  <s>The wife's rate is unknown, r</s>.
  

The owner's rate is  {{{1/10}}} jobs per hour.
The job is split into two parts of 4 hours each.


Instead of r, use 1/x for the wife's rate.


{{{(1/10)*4+(1/x+1/10)*4=1}}}, the two parts of the job, four hours just the owner and four more hours both wife and  owner, all to do the ONE job.  Solve the equation for x.