Question 535733
Part of the job done by the experienced man in one hour is 1/3. 
Part of the job done by the apprentice in one hour is 1/6.
Let x=their time together.  So part of the job done in one hour together is 1/x
Think: part done by man + part done by apprentice = part done together
1/3+1/6=1/x
Now multiply by 6x
2x + x = 6
3x = 6
x = 2

So they can get the job done together in two hours.