Question 887113
You have three solutions (2 correct and 1 incorrect) 
jon does 1/3 each hour and karen does 1/6 each hours

1/3+1/6=
common denominator
2/6+1/6=
3/6=
1/2 
Each hour they do 1/2 of the job. 

t/3+t/6 =1  job
2t/6+t/6=1
3t/6=1
t/2=1
t=2

or 
1/3+1/6=1/t
1/2 =1/t
2/6+1/6=1/t
3/6=1/t
1/2 =1/t
t=2