Răspuns :
a+b+c=10000
a+b=7200=>a=7200-b
b+c=5900=>c=5900-b
7200-b +b+5900-b=10000
b=12100-10000
b=2100=>a=7200-2100=>a=5100
=>c=5900-2100=>c=3800
a+b=7200=>a=7200-b
b+c=5900=>c=5900-b
7200-b +b+5900-b=10000
b=12100-10000
b=2100=>a=7200-2100=>a=5100
=>c=5900-2100=>c=3800
a+b+c=10000/a+b=7200/b+c=5900 si inlocuim in prima relatie a+b si iese 7200+c=10000 si c=2800/dupa inlocuim b+c pentru a afla a si iese a+5900=10000 si a e 4100/inlocuim in prima relatie la a+b+c=10000 si iese 4100+b+2800=10000/6900+b=10000/b=3100