一个梯形,上底与下底的和是60厘米,高15厘米,它的面积是 .
24: == ÷1.2= 折=75%
= ×=36÷ = :13.5.
÷20=0.4= %=2: .
已知m÷n=7…1,则m÷n=.
6÷ =0.75= %= : =.