Răspuns :

[tex]x + y = 500[/tex]

[tex]x + (500 - y) \times ( \frac{5}{13}) = 300 [/tex]

[tex]x + \frac{2500}{13 - 5y}13 = 300 [/tex]

[tex] \frac{8x}{13} = \frac{(3900 - 2500)}{13} [/tex]

[tex]8x = 600[/tex]

[tex]x = \frac{150}{2} [/tex]

[tex]x = 75[/tex]