This contains 11 pages, each containing 5 addition and 5 subtraction problems using variables. The 10 problems on each page have the same variable. I use this as 11 small centers in my classroom. Two of the pages contain negative integers for higher learners. I have mine on colored cardstock and laminated. Students play like a matching game. Students are to check each other on matches to make sure they are matches. I allow calculators for checking if needed, but stress to my students to do the math mentally first. Enjoy!