Răspuns :
6 +a < 13, a <13-6, a< 7
a-15<6, a<15+6, a<21
82-a>75, 82-75>a, 7>a, a<7
a-15<6, a<15+6, a<21
82-a>75, 82-75>a, 7>a, a<7
6+a<13
a<13-6
a<7
a=0,1,2,3,4,5,6
a-15<6
a<6+15
a<21
a=0,1,2,3.....20
82-a>75
82-75>a
7>a
a=0,1,2,3,4,5,6
a<13-6
a<7
a=0,1,2,3,4,5,6
a-15<6
a<6+15
a<21
a=0,1,2,3.....20
82-a>75
82-75>a
7>a
a=0,1,2,3,4,5,6