"So our rent is $1,500. You pay electric, I pay water, and she pays internet. 1500 divided by 3, minus 2 times the water bill, plus..."
This helps you determine the amount of rent you and the freeloading degenerates living with you should pay based on the bills each of you pay.
If I don't know the total rent for your house or shack or whatever, all of this is a sad waste of time.