Let L = {a 5k | for some k ≥ 1}. Show that the number of subsets of L is uncountable. B. Using part a) conclude that L has a nonregular subset

Question

I need help in these questions please Let L = {a^5k | for some k ≥ 1}. Show that the number of subsets of L is uncountable. b) Using part a) conclude that L has a nonregular