[tex]\it Vom\ nota\ numerele\ cu \ a,\ b,\ c\ \d si\ fie \ \ n,\ num\breve arul\ care \ se \ scade .\\ \\ \\ \left.\begin{aligned}a+b+c=72\ \ \ \ \ \ \ \ \ \ \ \ \\ \\ a-n=9 \Rightarrow \ a=9+n \\ \\ b-n=6 \Rightarrow \ b=6+n\\ \\ c-n=18 \Rightarrow c=18+n \end{aligned}\right\} \Rightarrow 9+n+6+n+18+n=72 \Rightarrow 33+3n=72 \Rightarrow \\ \\ \\ \Rightarrow 3n=72-33 \Rightarrow 3n=39\bigg|_{:3} \Rightarrow n=13\\ \\ \\ a=9+n=9+13\ =\ 22\\ \\ b=6+n\ =\ 6+13 = 19\\ \\ c=18+n=18+13=31[/tex]
