Statistics question

3. A biased die in favour of 4 where p(4) = = is thrown repeatedly until a 4 and a 5 have been obtained. The random variable A denotes the number of throws required. For example, for the sequence of results 4, 3, 2, 3, 4, 4, 5, the value of A is 7. Calculate E(M) and Var(M). [6 marks]