85-9=
34-7=
56+9=
56+5-20=
34+8=
28-7=
48-6=
9+5-8=
42+30=
78-8=
83-80=
48+(18-9)=
60-50=
70+20=
11-6+7=
73-(13+7)=
99=90+( )
60=66-( )
33=( )+( )