CREATE CONTEXT FREE GRAMMAR

For each of the following languages, create a context free grammar for it. Strings whose length is a multiple of 3. Strings of the form a^i b^j a^k such that i + k = j. Strings of a's and b's that belong to the language L*, where L = a^n b^n. (For example, aabbaaabbb would be in this language Strings of the form a^m b^n, such that m n + e. Strings of a's and b's that are not of the form a^n b^n (so any string of a's and b's, as long as it is not a string containing some number of a's and then an equal number of b's)