A={x|x apartine N, x | 18 si 2x +3 mai mic egal cu 15}
xl18, rezulta x={1,2,3,6,9,18}
2x+3<=15
2x<=12
x<=6, rezulta x={0,1,2,3,4,5,6}
A={1,2,3,6}, adica se iau elementele comune.
B={x|x apartine N , x|14 si 2x -1 <19}
xl14, rezulta x={1,2,7,14}
2x-1<19
2x<20
x<10
x={0,1,2,3,4,5,6,7,8,9}
B={1,2,7}
