Step-by-step explanation:
The sum of the hours Clara worked and the hours Erin worked is 9 5/6 and we know that Clara worked 4 1/3 hours. We can find out how many hours Erin worked by substracting the hours worked by Clara from the total number of hours:

To substract mixed numbers first we have to substract the whole part and then the fraction part:

And finally we can simplify the fraction part of the result:

Answer:
Erin worked 5 1/2 hours