Happy New Year! I am trying to fit a couple of equations that I need
into one formula and it is givin me some difficulty. To give the
example, I essentially have three equations for rental properties for a
new apartment complex: The steps include 1. How many units are rented
up, 2. How many are currently rented and, 3. The rental price. I have
broken this down into these three steps but combining them is very
difficult for me.

The first step, is how many units are newly rented that month. Say
month 1 is 25, month 2 is 20, month 3 is 10.

The next step is taking the balance of what is rented. Month 1 is 25,
Month 2 is 45 (25 + 20), Month Three is 55 (25+20+10), etc...

Step three is merely multiplying the units rented times the rental
rate.

Combining these is the hard part. The balance currently rented is
calculated by adding the previous month to the current month.(Step One
+ the previous month of Step 2) If I change this to a dollar amount,
(adding step 3), adding the previous month does not work since it is a
dollar amount.

I need to be able to find the balance of units rented without
referencing the previous month. Is this possible? Any suggestions
would be most welcomed!