(40-30)+(15-6)-10+4=10+9-10+4=19-10+4=13
§
10+(14-7)-(12-4)+6=10+7-8+6=15
16-7-2+(12-5)-(15-9)=7+7-6=14-6=8
(40-30)+(15-6)-10+4=10+9-10+4=19-10+4=13
§
10+(14-7)-(12-4)+6=10+7-8+6=15
§
16-7-2+(12-5)-(15-9)=7+7-6=14-6=8