Calculating Red Marbles

In a box, there are 40 marbles that are either red, blue, or green. If the number of blue marbles is 12 and the number of green marbles is 16, how many red marbles are in the box?

To solve this problem, you need to find the total number of red marbles by using the information given about the total and the other colors of marbles. Remember, the total number of marbles is the sum of red, blue, and green marbles.