17+2= 15-9= 5+7= 9-1+3=
19-6= 8-2= 8+4= 16-2+4=
16+4= 20-2= 6+7= 4+8-3=
11-4= 12-5= 8+3= 14+2-3=
17-3-7= 13+3-10= 11-4+6= 10-4+11=