If you want to find the horizontal side that you don't know, subtract 10 in from 17 in to get 7 in.
If you want to find the vertical side that you don't know, subtract 11 in from19 in to get 8 in.
You now know all the sides: add 10 in to 19 in to 17 in to 11 in to 7 in to 8 in to get your answer.