[tex]1)7.5 \: m \: ..... \: 45 \: lei \\ 11.25 \: m \: ..... \: x \: lei[/tex]
[tex]x = \frac{11.25 \times 45}{7.5} = \frac{506.25}{7.5} = 67.5 \: lei[/tex]
[tex]2)x - nr. \: total \: 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{2x}{3} \: (pagini \: necitite)[/tex]
[tex] \frac{2}{3} \times \frac{2x}{3} = \frac{4x}{9} \: (a \: doua \: zi)[/tex]
[tex] \frac{x}{3} + \frac{4x}{9} + 12 = x \: | \times 9[/tex]
[tex]3x + 4x + 108 = 9x[/tex]
[tex]7x + 108 = 9x[/tex]
[tex]9x - 7x = 108[/tex]
[tex]2x = 108[/tex]
[tex]x = \frac{108}{2} [/tex]
[tex]x = 54[/tex]
