Can the sum of two mixed numbers like 7 9/12 + 2 11/12 be equal to 2me i am in 4th grade i do not understand

If would help me explain if I break this into two pieces:

First:  add the whole numbers 7 + 2 = 9

Second:  add the fractions:  In this example, because both of the fractions has the same denominator (the bottom number), you can just add the top numbers (numerators) 9 + 11 to get 20/12.  Then, you need to simplify 20/12.  You do that by figuring out how many times 12 goes into 12 and how much is left over.  In this case, 12 goes into 20 one time with 8 left over.  So, 20/12 = 1 8/12.  

Now you add both of those two pieces together:
9 + 1 8/12 = 10 8/12.  
Now you need to take it one step further to simplify the 8/12 part of the answer.  8/12 can be simplified to 2/3 (divide the 8 by 4 to get 2 and divide the 12 by 4 to get 3), so your final answer is:
10 2/3.