先每种拿出10枚,还有2毛,也就是说用三种硬币凑两毛钱
20个一分；18个一分,一个两分；16个一分,2个2分；15个一分,一个5分；14个一分,3个2分；13个1分,1个2分,1个5分；12个1分,4个2分；11个1分,2个2分,1个5分；10个1分,5个2分；10个1分,2个5分；9个1分,1个5分,3个2分；8个1分,2个5分,1个2分；8个1分,6个2分；7个1分,1个5分,4个2分；6个1分,2个5分,2个2分；6个1分,7个2分；5个1分,1个5分,5个2分；5个1分,3个5分；4个1分,2个5分,3个2分；4个1分,8个2分；3个1分,1个5分,6个2分；3个1分,3个5分,1个2分；2个1分,2个5分,4个2分；2个1分,9个2分；1个1分,1个5分,7个2分；1个1分,3个5分,2个2分；4个5分；10个2分
一共28种