Question 437121
Assume each works on the same driveway.

Sue, 30 minutes for the job
Jim, 35 minutes the same job

The two of them working together,  {{{1/30+1/35}}} driveway per minutes


{{{(7/7)(1/30)+(6/6)(1/35)}}}

{{{13/210}}}

or looking at reciprocal

{{{210/13}}} minutes per driveway

 approximately 16 minutes