**inmultesti pe diagonala
[tex] \frac{3}{a} = \frac{b}{9} [/tex]
[tex]a \times b = 9 \times 3[/tex]
[tex]a \times b = 27[/tex]
[tex] \frac{a \times b}{a \times b + 3} [/tex]
**inlocuiesti a×b cu 27
[tex] \frac{27}{27 + 3} = \frac{27}{30} [/tex]
**se simplifica fractia prin 3
[tex] = \frac{9}{10} [/tex]
