A good memory is a good thing to have. It can often help you to solve complicated problems since it enables you to keep track of many things at once. The game of Concentration involves using your memory to keep track of the location of items (in this case the values of equations).
In this version of the game of Concentration you will have to keep track of the location of addition and subtraction equations. Matching equations are those with the same value when solved. For instance, consider these equations which all have 8 as their solution:
3 + 5 = 8 9 - 1 = 8 6 + 2 = 8 4 + 4 = 8 10 - 2 = 8 7 + 1 = 8