Adding and subtracting mixed numbers with unlike denominators

The topic  is under the 5th Grade Math Mission. This exercise practices arithmetic with mixed numbers.

Types of Problems
There is one type of problem in this exercise:


 * 1) Find the sum or difference: This problem has an arithmetic problem posed which is either addition or subtraction of two mixed numbers. The student is expected to type the correct simplified mixed number answer in the available space.Addsubmix1.png

Strategies
This exercise is medium to get accuracy badges because some care needs to be taken when "distributing" through the mixed number. Speed badges are medium because of the amount of time it takes to perform these operations.
 * 1) The answer must be submitted in a mixed number form, example, a b/c.
 * 2) If you are familiar with TI83Basic, see if you can figure out how to use the code to insert three numbers and have the calculator arrive at the answer.
 * Prompt A,B,C
 * int(A+B+C)->D
 * Disp D,(A+B+C-D)>Frac