When removing the bracket, remove the bracket again.

The plus sign before the brackets is removed directly.

The symbols in brackets remain unchanged.

The minus sign before brackets should be determined according to the sign of the first number in brackets.

The symbol of the first number is-

Change the symbol to+

The symbol of the first number is+

Change the sign to-

Other symbols in brackets will change accordingly.

Multiplication and division

Should be calculated first.