I have to find the ending inventory and COGS with the LIFO and FIFO methods.

The company has four purchases

1,000 units at $10 ea.	Beginning Inventory	$10,000
1,000 units at $10 ea.	Purchase	$10,500
500 units at $11 ea.	Purchase	$5,500
1,000 units at $11.25 ea.	Purchase	$11,250
Total: 3,500 units		Total: 37,500

The ending inventory consists of 500 units, i.e, they sold 3,000 units.

In every video I watch to do this, they do not have leftovers and actually need to take away from other purchases. How can I solve this with 500 units when purchases are larger?