袋中原来有红球x个,黄球y个
x-1=1/7(x+y)
x=1/5(x+y-2)
解得x=4.5,y=20
题目数据有问题应该50个球呀袋中原来有红球x个，黄球y个x-1=1/7(x-1+y)x=1/5(x+y-2)解得x=4,y=184+18=22 袋中原来共有22个球我验算过了 确实不对啊袋中原来共有22个球这个应该对了