解:设每天长出x草,
6(27-x)=9(23-x)
162-6x=207-9x
3x=45
x=15
原有草数:162-6x
= 162-90
= 72
答案:72/(21-15)
= 72/6
= 12
很简单的
解:23*9-27*6)/(9-6)=15
(27-15)*6=72
72/(21-15)=12
(23*9-27*6)/(9-6)=15
(27-15)*6=72
72/(21-15)=12
就是这样的了
15
(23*9-27*6)/(9-6)=15
(27-15)*6=72
72/(21-15)=12
14天