Nichols Company had 600 units of Dink in its inventory at a cost of $12 each. It purchased 900 more units of Dink at a cost of $18 each. Nichols then sold 1,050 units at a selling price of $30 each. The LIFO liquidation overstated normal gross profit by

I know that the correct answer is $900 but I would like to know how to get there.

Thank you!!