Răspuns:
13-6=10-6+3=4+3=7
17-9=10-9+7=1+7=8
14-8=10-8+4=2+4=6
13-6=13-3-3=10-3=7
17-9=17-7-2=10-2=8
17-8=17-7-1=10-1=9
