Exercise Help

Sir, Im doing an exercise about allocate and apportion overheads to different departments.

If in the question, they provide the budgeted overhead for the following months of canteen is 120,000$ and also the canteen takings is budgeted as 20,000$. And then they ask to allocate the overheads of the Canteen to other departments.
Are we suppose to deduct the canteen takings of 20,000$ out of the cost of 120,000$ before allocating the canteen overheads to other departments?