Răspuns:
[tex] \frac{6}{a - 3} \leqslant \frac{12}{4} \\ (a - 3) \times 12 = 6 \times 4 \\ 12a - 36 = 24 \\ 12a = 24 + 36 \\ 12a = 60 \\ a = 5[/tex]
[tex] = > \frac{6}{5 - 3} \leqslant \frac{12}{4} \\ \frac{6}{2} \leqslant 3 \\ 3 \leqslant 3 \\ = > 3 = 3[/tex]