please help, if dont know it, DO NOT do it.

Question 7 (3.125 points) Listen At May 1, 2012, Yeart had beginning inventory consisting of 100 units with a unit cost of $10. During May, the company purchased inventory as follows: 200 units at $10 300 units at $8 The company sold 500 units during the month for $15 per unit. Yeart uses the average cost method. The average cost per unit for May is 1) $7.50 2) $7.60 3) $7.0 4) $9.00