Răspuns:
10, 11, 12, 13, 20, 21, 22, 30, 31, 40
Explicație pas cu pas:
a+b ≤ 4
a=1 -> 1+b ≤ 4
b ≤ 3 => b ∈ {0; 1; 2; 3}
a=2 -> 2+b ≤ 4
b ≤ 2 => b ∈ {0; 1; 2}
a=3 -> 3+b ≤ 4
b ≤ 1 => b ∈ {0;1}
a=4 -> 4+b ≤ 4
b ≤ 0 => b ∈ {0}
Deci numerele sunt: 10, 11, 12, 13, 20, 21, 22, 30, 31, 40
