Răspuns:
[tex]x + \frac{10}{100} x - \frac{5}{100} (x + \frac{10}{100} x) = 209[/tex]
[tex]x + \frac{1}{10} x - \frac{1}{20} (x + \frac{1}{10} x) = 209[/tex]
[tex]x + \frac{1}{10} x - \frac{1}{20} x - \frac{1}{200} x = 209[/tex]
[tex]200x + 20x - 10x - x = 41800[/tex]
[tex]209x = 41800[/tex]
[tex]x = 200[/tex]