ab2 + 2ba +
cd3 3dc
------ -------
a + c = 5 (a = 1 c = 4) (a = 2 c =3) 2variante
------------------------------------------------------------------------------
b + d ≤ 9 b =0 d ∈ {0,1,2....9} 10 variante
b = 1 d∈{0,1,2.....8} 9 variante
b = 2 d ∈ {0,1,2,....7} 8 variante
----------------------------------
b = 9 d = 0 1 varianta
nr. perechi = 2(10 + 9 +......+1) = 2·10·11/2 = 110