Answer:
5 5/11 hours
Step-by-step explanation:
So, there is a trick to doing this.
You would first need to get their work rate into the same measurements.
That's why we will find out how much they each work in one hour.
Tommy does 1/12 of the work in one hour while Robert does 1/10.
Here we can add them both up to make 11/60.
They finish 11/60 of the work in one hour.
They finish the job in 5 5/11 hours.
