Răspuns :
a+b+c=840
a+b=642
b+c=553
642+c=840
c=840-642
c=198
a+553=840
a=840-553
a=287
b+198=553
b=553-198
b=355
Verificare: 287+198+355=840
a+b=642
b+c=553
642+c=840
c=840-642
c=198
a+553=840
a=840-553
a=287
b+198=553
b=553-198
b=355
Verificare: 287+198+355=840
a+b+c=840
a+b=642
642+c=840
c=840-642=198
c=198
b+c=553
b+198=553
b=553-198=355
b=355
a+355+198=840
a+553=840
a=840-553=287
a=287
287+355+198=840
a+b=642
642+c=840
c=840-642=198
c=198
b+c=553
b+198=553
b=553-198=355
b=355
a+355+198=840
a+553=840
a=840-553=287
a=287
287+355+198=840