14-6= 15-9= 11-7= 12-9=
13-5= 11-9= 11-3= 15-8=
14-8= 13-8= 15-6= 11-5=
12-5= 16-7= 18-9= 14-7=
12-8= 12-3= 14-9= 17-8=