A tea shop owner is purchasing two kinds of tea leaves for his business.  Green tea leaves come in 16-ounce bags, and oolong tea leaves come in 20-ounce bags.  The maximum order size allowed is 640 ounces, and the owner wishes to purchase at least three times as many ounces of green tea leaves as ounces of oolong tea leaves.  If x and y represent the number of bags of green and oolong tea leaves, respectively, that the owner will purchase, which of the following systems of inequalities represents this scenario?

ประโยคนี้แปลว่าอะไรคะ at least three times as many ounces of green tea leaves as ounces of oolong tea leaves
รบกวนช่วยเขียนเป็นสมการให้ด้วยค่ะ