The price of this Bill differs slightly due to the price of each item is different. Now that I've included a wide range of items in a row I used an average of the price of the item.
The price of the bill is slightly different because of the price of each item is different. When I combine multiple items in a row, I use an average of the prices of goods.
The price of both invoice is slightly different, because the price of each item is different. When I include a variety of items in one row, I use the average price of the goods.