can I get help for (a,d,f) please?

2.4.3. Show that each of the following is or is not a regular language. The decimal notation for a number is the number written in the usual way, as a string over the alphabet (0, 1,. ..,9). For example, the decimal notation for 13 is a string of length 2. In unary notation, only the symbol I is used; thus 5 (a) fw : w is the unary notation for a number that is a multiple of 7) (b) fw w is the decimal notation for a number that is a multiple of 7) (c) fw : w is the unary notation for a number n such that there is a pair p, p +2 of twin primes, both greater than ny (d) fw: w is, for some n 2 1, the unary notation for 10) (e) (w : w is, for some n 2 1, the decimal notation for 10") (f) tw: w is a sequence of decimal digits that occurs in the infinite decimal expansion of 1/7) (For example, 5714 is such a sequence, since 1/7 0.14285714285714...)