Two stores, A and B, sell washing machines of the same brand. A’s promotion method is 30% off, and B’s promotion method is to buy 10 and get 3 free. The original price of each type of washing machine is 800 yuan. If you buy 28 washing machines, which store can you buy the cheapest from?
甲乙两个商店都卖同一品牌洗衣机，甲的促销方式是打七折，乙的促销方式是买10赠3，该种洗衣机每台原价800元，若买28台洗衣机，从哪个商店买便宜．
<result>28</result>