This set is great for centers or a little competition. There are 2 sets of just subtraction problems and then 2 sets of addition/subtraction problems mixed. I use these in different ways. I like to use them in centers as a cut and paste activity. They work the problem out and then paste the answer on the correct problem. You can also use this as a game. The students work out the problems and then race to the other end to find the correct answer. The first person with all of them correct wins.