Question 80128
No.  When the denominators are the same adding or subtracting 
fractions is like adding or subtracting cars. 
4/xy + 6/xy = 10/xy
just like
4 cars + 6 cars = 10 cars.
---------
Similarly 
6/xy - 4/xy = 2/xy
just like
6cars - 4cars = 2cars
===========
cheers,
Stan H.