用竖式计算下面各题800﹣260=680+270=74﹣16=25+36=
3:5==9: == .
=0.375=12÷ = %=0.45= %= ÷ .
= ÷ = = % ÷ =0.25== %
在括号里填上合适的数. 6÷12=7÷16=40÷82= ÷5=11÷ = ÷ =.
把下列分数写成两个数相除的式子. (1) (2) (3) (4).