笼子里有若干只鸡和兔,从上面数,有16个头,从下面数,有52个脚,那么鸡有 只,兔有 只.
÷ =0.75== %= 折.
: = ÷10= %
==4÷ =8: = %
0.625== = ÷40=.
3:4= :12=12÷ == %