8.6扩大 倍是8600,4.2缩小到原来的 是0.42.
:12=6÷ = 填小数= 折=75%.
=0.4==12÷ = %= :25.
= (小数)= (百分数)=12: = 折.
0.75== ÷16=27: = %.
= : =33÷ = %