The first two of these three questions are mainly simplified by removing brackets. Finally, divide a number by its reciprocal, turn the division symbol into a multiplication symbol, and then make a simple calculation by multiplication and division.

By removing the brackets, remove the brackets after the plus sign and the multiplication sign, and the numbers in the brackets remain unchanged. Remove the brackets after minus sign and division sign, and the symbols in front of the numbers in brackets will change, that is, the numbers in brackets used to be plus sign, minus sign, plus sign, multiplication sign, division sign and multiplication sign.