Given a and b such that (x^3)^a = x^15 and (x^b)^4 = x^8 for all positive x, what is a - b?

This is what i found “an explicit formula designates the nth term of the sequence, as an expression of n (where n = the term's location). it defines the sequence as a formula in terms of n. this example is an arithmetic sequence(the same number, 5, is added to each term to get to the next term).” i hope this you for what your looking for. can you plz mark me brainliest?

Answer is negative 2