Looking for Answers about Suntex International Inc. 24 Game: Single Digits (48 Cards)?

Your object is simple: make the number 24 using the four numbers on a game card. Subtract, add, multiply and divide using all four numbers---- but use each number only once! There's at least one solution to each card. Cards have 3 levels of difficulty. Ages 9 & up. 48 self-check cards (24 easy, 48 medium, 24 tough). Cards are 4" x 4".