which comes next
1/3, 4/9, 5/9 -----
4/40, 2/5,
3/7, 8/14, 5/7
choices
2/3, 1/5, 36/42, 8/28,
rewrite as
3/9, 4/9, 5/9, ...
1/10, 4/10, ...
3/7, 4/7, 5/7 ...
the 1st and 3rd are easy, but I'd have to pick 1/5 for (b) just because it's the only one with a 5 in the denominator. No idea on the pattern.