“第二季度用煤量比第一季度减少了5%”,也就是 用煤量是第一季度用煤量的5%.
12: =0.375=45÷ = :56=.
15:90= %==6÷ = :12.
=:0.5= ÷ .
:8===9÷ =27: .
=== ÷5=.