Răspuns:
Explicație pas cu pas:
[tex]3\leq \dfrac{2(2x-5)}{3}-7< 29\dfrac{2}{3}, ~~~\dfrac{9}{3}\leq \dfrac{4x-10-21}{3}< \dfrac{29*3+2}{3}~|*3,~~~\\9\leq 4x-31< 89~|+31[/tex]
9+31≤4x<89+31, ⇒40≤4x<120 |:4, ⇒10≤x<30.
Deci, A=[10; 30).
A∩N={10, 11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29}
nr de elemente este n=29-10+1=20
nr de cazuri favorabile, m=4, pentru numerele 11,12,21,22.
Deci P=m/n=4/20=1/5=20/100=20%
