notam cele doua numere a si b
[tex]a+b=280, dar \frac{a}{3} =\frac{b}{4} => a=\frac{3b}{4}[/tex], astfel inlocuim in relatia initiala si obtinem:
[tex]\frac{3b}{4}+b=280 => 3b+4b=1120 => 7b=1120=>b=\frac{1120}{7} => b=160[/tex]
aflam pe a in functie de b : [tex]a=\frac{160*3}{4} = 120[/tex]
a=120, b=160
