you didnt give us information about what you want to do with this answer. But one thing you could do is split the first bracked (x-4y) on the second bracket (5x-9y). So you would then have x(5x-9y) -4y(5x-9y). then 5x^2-9xy -20xy + 27y^2.
5x^2 - 29xy +27y^2. But this is just one example tell us more.