(1)一张电话卡的面积大约是40 .(2)教室长8 ,宽6 ,面积是 .
12: =0.375=45÷ = :56=.
15:90= %==6÷ = :12.
=:0.5= ÷ .
:8===9÷ =27: .
=== ÷5 =.