How many screws are needed per box of slatwall?
If a customer buys 1 box of slatwall then they need 1 box of screws. If a customer buys 2 boxes of slatwall then they need 2 boxes of screws. If a customer buys 3 boxes of slatwall then they need 2 boxes of screws.
You will have to continue to do the math depending on the boxes.