把算式646﹣247=399,改写成一道加法算式和一道减法算式分别是 , .
: =0.25= ÷16= %==.
:32===6÷ = .
= :24=0.625=20÷ = .
比的前项是0.4,比值是,则比的后项是 .
=0.75= ÷12=1.8: = :24.