The monthly cost of maintenance is calculated by dividing the annual cost in cell C13 by 12 and entering the formula in cell C22.
To compute the monthly cost of maintenance, you would take the total annual cost and divide it by 12 to find the cost per month. In the context given, where the annual cost is in cell C13, you would enter the following formula in cell C22:
=C13/12
This will give you the monthly maintenance cost you're looking for. This sort of calculation is quite usual when budgeting and managing finances, either in personal or business contexts.