比的前项缩小3倍,后项扩大3倍,那么它的比值缩小9倍. .
= : =15÷ ==0.6.
4÷5==== ÷80.
6÷ ===≈ .(保留三位小数)
=0.375=12÷ = : .
= %=8÷ =4: = (填小数)