16-7= 14-8= 10-8=
11-8= 13-7= 12-8=
8+=11 7+=16 8+=13
11-8= 16-7= 13-8=
-7 =
-8 =
13-813-7 15-88 14-75
12-711-7 17-812-7 16-910-7
=
8元 7元