Notam numarul total de pagini cu x .
[tex] \frac{3}{5} x +30 = \frac{2}{3} x[/tex]
[tex] \frac{3}{5}x - \frac{2}{3}x= -30 [/tex]
Aducem la acelasi numitor .
[tex] \frac{9x-10x}{15}=-30 [/tex]
[tex]-x=-30 [/tex] · 15
[tex]-x=-450[/tex] ==> x=450 ==> cartea are 450 de pagini .