Answer:
square foot per hour
Step-by-step explanation:
The total area covered = 34 square foot
Time taken = 12 hours
This implies that it takes 12 hours to cover 34 square foot.
Using proportionality,
12 hours ---------------------------------------> 34 square foot
Dividing both sides by 12
---------------------------> 
1 hour --------------------------------------->
square foot per hour
The unit rate in square feet per hour is
square foot per hour