83. Please use the following 4 numbers (each number must be used exactly once, and the order can be changed), as well as “ $+$ 、 $-$ 、 $\times 、 \div$ ” and parentheses, to make 24:
(1) $7 、 12 、 9 、 12$;
(2) $3 、 9 、 5 、 9$.