7+6= 6+8= 9+=13
+8=15 +7=12
5+915 14-94 168+8 917-9
(棵)
( )?
12-8=
13-5=
10+9=
14-5=
18-9=
5+8=
12-3=
15-6=
13-8=
17-9=
14-7=
16-8=
+5=13 -6=4 6+=18 13-=6
+9=16 -8=4 7+=16 17-=8
16-7=
15-8=
16-6=
10-3=
11-2=
9+6=
6+8=
7+9=
8+8=
7+6=