Make 24 out of 4 cards using arithemtic signs and brackets

In this game you have 4 cards, and you are required to use these 4 cards and arithmetic signs to make a formula that gives 24. A is 1, J is 11, Q is 12, K is 13.

You can use add, subtract, multiply, divide and brackets in the formulas, and all the four cards must be used.