12-5= 13-9= 14-6= 15-7= 14-7+6=
15-9= 11-6= 16-5= 13-6= 12+8-5=
14-9= 12-8= 17-9= 16+4= 19-7+3=
19-8= 16+2= 18-4= 16-9= 11+8-9=