Răspuns:
[tex]x - y = 2 \times \frac{x}{3} [/tex]
[tex]x - y = \frac{2x}{3} [/tex]
[tex] \frac{3x}{3} - \frac{2x}{3} = y[/tex]
[tex] \frac{x}{3} = \frac{y}{1} [/tex]
[tex]x = 3y[/tex]
[tex]x + y = 72[/tex]
[tex]3y + y = 72[/tex]
[tex]4y = 72[/tex]
[tex]y = 18[/tex]
[tex]x = 3 \times 18[/tex]
[tex]x = 54[/tex]
