12-7 = 14-5 = 4+7 = 17-8=
18-9= 11-2 = 9+8 = 15-6=
6+5-4 = 3+7+4 = 20-1-10=
15-8+2 = 11-7+5 = 19-9+3=
11-=5 8=16 - 7+=18–5
>> > >
118 13-413-8 6+814 78+7-5
17-715-7 16-98 14-79 9+612-8