用一根长28厘米的铁丝围成一个正方形,正方形的边长是 ,面积是 .
15÷20==18: = %= (填小数)
=0.25= :32=8÷ = %= 折.
== ÷ = (小数)
÷5== =0.6=15÷ .
==0.25==.