有12个△,△的个数是○的2倍,○有 个.
12: =0.6==6÷ = %
÷20=6: == %= 成=0.15.
:16==24÷ = %
9÷ = :48=0.75= %= 折数.
:12=6÷ = 填小数= 折=75%.