2+8=
12-6=
14-5=
18-3=
6+13=
12+7=
16-7=
11-8=
12-9=
13-6=
12-7=
14-9=
9+4=
12-10=
5+8=
18+5=
11-7=
14+3=
5+7=
19-0=
14-7=
0+7=
18-( )= 10
( )+4=17
7+( )=13
问题: