Răspuns:
a + b = 11
=> a aparține {2, 3, 4, 5, 6, 7, 8, 9}
=> b = 11 - a
b = 11 - 2 => 9
b=11 - 3 => 8
b = 11 - 4 => 7
b = 11 - 5 => 6
b = 11 - 6 => 5
b = 11 - 7 => 4
b = 11 - 8 => 3
b = 11 - 9 => 2
=> b aparține {9, 8, 7, 6, 5, 4, 3, 2}
729, 738, 747, 756, 765, 774, 783, 792