[latex] frac{7x+21}{x+2}= frac{x+3}{5} \ frac{7(x+3)}{x+2}= frac{x+3}{5} \ Produsul~mezilor~cu~al~extremilor: \ 5*7(x+3)=(x+3)(x+2) \ 35(x+3)=(x+2)(x+3) \ x+2=35 \ oxed{x=33}[/latex]