7537+20
8392-8
69角6元9角
45+5690-40
68-4064
39分4元
38 - 5 + 20 = 30 + 12 - 7 = 39 +(24 + 6)=
50 + 45 + 5 = 60 +(18 - 8)= 34 -(3 + 6)=
35+>40 70-<62
82-=72 35+=35-