3.7993.8 4吨 500 千克4.05 吨
7.5+1.9=
10-8.3=
3-0.78=
19×30=
75÷15=
①35.9+0.41= ②48.5-19.68=
①8.47+12.53-1.2 ②50-19.8-20.2 ③19.4+4.58+5.42