It's 4/5....you just find out what each of the denominators are equal to....so they are both factors of 45......so you take the one with 2/5 and multiply by 9 on top and bottom and then take 2/9 and multiply it by 5 on top and bottom so you have 18/45 and 10/45....so now you take the to and add them up to get 28/45 and now you can simplify if necessary