Formulate rules for expanding parentheses preceded by a plus and a minus sign.

When opening parentheses, which are preceded by a plus without any multiplier, you can painlessly remove the parentheses without changing anything – the result of the expression will not change from this. If, however, there is a plus in front of the parenthesis with a factor outside the parenthesis, then when opening the parenthesis, you need to sequentially multiply all the arguments in the parenthesis by this factor.

When opening parentheses that are preceded by a minus without any factor, the parentheses can be removed by reversing the argument signs in the parenthesis. If there is a minus in front of the parenthesis with a factor outside the parenthesis, then when opening the parenthesis, you need to sequentially multiply all the arguments in the parenthesis by this factor, not forgetting the rule of multiplication by a negative number.