[tex]\hbox Se aduna toate cele 3 relatii:} \\\\ a+b=571 \\ b+c=326 \\ a+c=523 \ \\ ======== \\ 2a+2b+2c=571+326+523 \\\\ 2(a+b+c)= 1420 \ \ \ |:2 \\\\ a+b+c=710 \\\\ ====\ \textgreater \ c=710-571 \to 139 \\\\ ====\ \textgreater \ a=710-326 \to 384 \\\\ ====\ \textgreater \ b=710-523 \to 187 \\\\\\ a-b-c= 384-139-187= 384- 326 \\\\ \boxed{a-b-c=58} [/tex]
