Răspuns :

[tex] \frac{a-1}{2}= \frac{3}{b+1} =>(a-1)(b+1)=6[/tex]
Avem urmatoarele variante:
1) a-1=1, a=2; b+1=6, b=5;
2) a-1=2, a=3, b+1=3, b=2;
3) a-1=3, a=4, b+1=2, b=1;
4) a-1=6, a=7, b+1=1, b=0.
Solutie: (a,b) ∈ {(2,5);(3,2);(4,1);(7,0)}.