Formula help needed
 

I am having trouble creating a formula that will help me create a carry
forward stream of payments.

For example, I have the following columns:

Gross Sales - units sold x price per unit

Gross Receipts - Cash collected

Carry forward - Amount of cash that will be paid in future payments

The variables a

Number of payments

% of customers paying full price up front

I am trying to create a formula that will allow me to alter the
variables and yet automatically calculate the future stream of
payments.

Meaning, if 50% of the customers pay me full price up front, and
another 50% pay only half price up front and the rest evenly in future
months how do I calculate that?