The shopping mall holds a promotional activity. When purchasing goods, you can get a 20-yuan shopping coupon for every 50 yuan in cash spent, and a 50-yuan shopping coupon for every 100 yuan in cash spent. Now Xiao Ming wants to buy 37 items worth 10 yuan. How should he buy them so that he can spend the least amount of money?
商场举行促销活动，在购买商品时，每消费50元现金就可以得到一张20元的购物券，每消费100元现金就能得到一张50元的购物券．现在小明要买37件10元的商品，他该怎样去买才能让花出去的钱最少？
<result>25</result>