Răspuns :
a+b=15
b+c=13
a+c=14
a=15-b
b+c=13
15-b+c=14 b-c=1
adun ultimele doua ecuatii si avem 2b=14 b=7
a=15-7=8
b+c=13 c=13-7=6
5a+5b+5c=5(8+7+6)=105
3a+3b+3c=3x21=63
b+c=13
a+c=14
a=15-b
b+c=13
15-b+c=14 b-c=1
adun ultimele doua ecuatii si avem 2b=14 b=7
a=15-7=8
b+c=13 c=13-7=6
5a+5b+5c=5(8+7+6)=105
3a+3b+3c=3x21=63