please solve

Using weighted average, what is gross margin? Date Source Units Purchased Cost Per Unit Total Cost 1/1/2011 950 $14 Beginning Inventory Purchase $13,300 2/1/2011 800 $10 $8,000 $12 $18,000 3/1/2011 Purchase 1,500 Total Goods Available for Sale 3,250 Units sold 2300 $39,300 $18 O $13,588 $13,500 O $15,400 $39,300 O $12,265