a<5=>a€{ 1, 2, 3, 4}
b<7=>b€{1, 2, 3, 4, 5, 6}
a)
[tex] \frac{1}{2} \frac{1}{3} ... \frac{1}{6} [/tex]
[tex] \frac{2}{3} \frac{2}{4} ... \frac{2}{6} [/tex]
[tex] \frac{3}{4} \frac{3}{5} \frac{3}{6} [/tex]
[tex] \frac{4}{5} \frac{4}{6} [/tex]
[tex] \frac{5}{6} [/tex]
b)
[tex] \frac{1}{1} \frac{2}{2} \frac{3}{3} \frac{4}{4} [/tex]
c)
[tex] \frac{2}{1} \frac{3}{1} \frac{4}{1} \frac{3}{2} \frac{4}{2} \frac{4}{3} [/tex]
