周长相等的两个长方形它们的长和宽也一定相等. .
= : =15÷ = %
= :20=4.5÷ = %=0.5 .
15÷ ==9: = %=0.75.
9: ==36÷ = :45= (填小数)
%= ÷8==0.75= (填成数).