hey guys ive got a problem

If z = 3− i and w = 1+3i, evaluate Im (z∗w)/(2z − 3w) *=conjurate(ithink)

wehn i expand the top line i get 10i/3-11i however it says the answer is 3/13??? ive tired multipling everything by 3+11i however im stuck. any help would be good. thanks