含盐率20%的盐水中,加入4克盐和16克水,这时盐水中含盐率还是20%. .
÷ == %== : = 折= 成.
= ÷32=( 0.125 )填小数=6:( )=12.5%.
== :32=15÷ = (填小数)
=18: =0.6== %= 折.
÷6=6: =1.5= %