If you want it the long way, you can go like this:
1. (5x)(-6y)(10y)(-2x)
The subtracted numbers becomes negative.
2. Just put the numbers with the same variables together.
(5x-2x)(-6y+10y)
Numbers that are positive becomes addition
4. Do the parenthesis. (Only numbers with the same variables should be added/subtracted together.)
5x-2x becomes 3x and -6y+10y becomes 4y.
The answer is 3x+4y.
I explained in a confusing way, but basically, just put together the numbers with the same variables (letters).