June1 inventory 225 $5 $1125
June 12 purchases 375 $6 $2250
June 23 purchases 500 $7 $3500
June 30 inventory 180 $0 $0


What's the average cost EI [ending inventory] and average cost COGS?

225+375+500-180=920 (unit sold)
average cost: (1125+2250+3500)/(225+375+500)
COGS is whatever the result of the above unit cost times 920 units.