Răspuns:
card (S ∩ N) = 4
Explicație pas cu pas:
[tex]\frac{3x - 1}{3} + \frac{x - 21}{6} \leqslant 0 \\ 2(3x - 1) + x - 21 \leqslant 0\\ 6x - 2 + x - 21 \leqslant 0 \\ 7x \leqslant 23 = > x \leqslant \frac{23}{7} \\ 3 < \frac{23}{7} < 4[/tex]
S ∩ N = {0; 1; 2; 3}
card (S ∩ N) = 4
