一个长5cm、宽3cm的长方形按3:1放大,得到的长方形的长是 ,宽是 ,面积是 .
= ÷ =9: == %= 折.
= ÷ = (填小数)
12÷ =0.75== :36= %
÷ =0.125=2÷ == %
: == ÷20= 折.