When removing the bracket, please pay attention to the following principles:

There is a "+"before the brackets. After removing the brackets and the "+"sign in front of them, the symbol of the original brackets remains unchanged.

The "-"sign precedes the brackets. After deleting the brackets and the "-"before them, all the symbols in the original brackets will be changed (instead of the original symbols, for example: -(x-y) =-x+y).