假設(shè)1隊(duì)人數(shù)x
1隊(duì)是二隊(duì)的三分之四,也就是2隊(duì)是1隊(duì)的四分之三
1隊(duì)是三隊(duì)的四分之五,也就是3隊(duì)是1隊(duì)的五分之四
1隊(duì)+2隊(duì)+3隊(duì)=(1+3/4+4/5)x = 51x/20
因?yàn)?隊(duì)一共100人,所以1隊(duì)+2隊(duì)+3隊(duì)小于100人即：
51x/20 < 100
另外,因?yàn)槿藬?shù)是整數(shù),所以x是正整數(shù)且51x一定能被20整除.
很顯然,x=20
1隊(duì)：20
2隊(duì)：15
3隊(duì)：16
4隊(duì)：49