SumIf: "I" The Order Quantity To Automatically

I have inserted the sheet. As you can see sheet1 has some Products codes in A, Products in B, Layer Quantity in C, In G and H I have Sales and Stock and in I is the order quantity. I would like for I the order quantity to automatically do the order when the sales and stock are shown in G + H. I need this to be based on the Layer Quantity in C.

So ( I5 ) would be 18 because I have 20 left and sold 17, the layer is 18 and 18 would cover the sales. I 14 would be 90 because 90 + the stock of 35 is 125 double the sales going up in 15s whick is the layer quantity. I need the Order quantity and the stock left to be at least double the sales but go in layer quantity