Răspuns :
a+b=1580
a-b=720=>a=b+720
720+2b=1580
2b=860
b=430
a=430+720
a=1150
Verificare: 1150+430=1580
a-b=720=>a=b+720
720+2b=1580
2b=860
b=430
a=430+720
a=1150
Verificare: 1150+430=1580