[tex]x - nr. \: de \: pagini [/tex]
[tex] \frac{1}{3} \times x = \frac{x}{3} \: (prima \: zi)[/tex]
[tex]x - \frac{x}{3} = \frac{3x}{3} - \frac{x}{3} = \frac{3x - x}{3} = \frac{2x}{3} \: (rest)[/tex]
[tex] \frac{ \frac{2x}{3} }{2} = \frac{2x}{3} \times \frac{1}{2} = \frac{x}{3} \: (a \: doua \: zi)[/tex]
[tex] \frac{x}{3} + \frac{x}{3} + 35 = x \: | \times 3[/tex]
[tex]x + x + 105 = 3x[/tex]
[tex]3x - x - x = 105[/tex]
[tex]x = 105[/tex]
