x 1
---- - -------
5y 4
-----------------
3 2
--- - ----
4y x
find common denominators for both fractions:
4x - 5y
---------
20y
------------------
3x - 8y
---------
4xy
multiply by the reciprical of the bottom:
4x - 5y 4xy
--------- * ----------
20y 3x - 8y
reduce the fractions by 4y:
(4x - 5y) x
---------------
5(3x - 8y)
multiply out the top and bottom:
4x^2 - 5xy
-------------
15x - 40y