I need the answers to be explained.

The Amazing Ginzu Knives (AGK) Corporation uses a periodic inventory system and buys 300 units of merchandise in January at $5 each. AGK buys 500 units at $4 each in February and 200 units at $6 each in March. The company had no beginning inventory. Consider each question independently.

6. AGK sells 300 units during this quarter. If AGK uses the LIFO method, what is its cost of goods sold for the quarter?

A. $1,600

B. $1,400

C. $1,500

D. $1,800

7. AGK sells 150 units during this quarter. If AGK uses the weighted average method, what is its cost of goods sold for the quarter?

A. $600

B. $705

C. $750

D. $900

8. AGK sells 300 units during this quarter. If AGK uses the FIFO method, what is its cost of goods sold for the quarter?

a. $1,600

b. $1,400

c. $1,500

d. $1,800