2.05÷(1.5+0.55)×99% (×﹣)÷87.5%×+12.5%× ×(+)÷.
=0.375=21÷ =6: = %.
5:6可以写成5÷6,比值是1.2.所以2:3:4=2÷3÷4. .
3÷8═= ÷24= %= :56.
3:4= :8=9: == %
3÷ == :12=七成五= %