[tex]a = 3b \\ \frac{a + b}{2} = 84 \\ rezulta \: ca \: a + b = 84 \times 2 \\ a + b = 168 \\ daca \: a = 3b \: rezulta \: 3b + b = 168 \\ 4b = 168 \\ b = \frac{168}{4} \\ b = 42 \\ a = 3b \\ a = 3 \times 42 \\ a = 126 \\ \\ verificare \\ \frac{a + b}{2} = 84 \\ \frac{126 + 42}{2} = 84 \\ \frac{168}{2} = 84 \\ 84 = 84[/tex]
