帮我算算以下的(西马)
现在这个卖家有买三免一优惠的活动,麻烦帮我问问卖家怎样算。
https://world.taobao.com/item/53 ... 578408299.61.IJ2naX

https://world.taobao.com/item/53 ... 578408299.65.YdIigY

https://world.taobao.com/item/53 ... 578408299.85.BKWa6b