Adding And Subtracting Fractions With Like And Unlike Denominators

Addition:

Like Denominators: To add with like denominators, you add the numerators only. 

For example, 
5/12 + 2/12 = 7/12
Notice how I only added 5+2? That's because you do not add denominators. It's the equal pieces the whole is cut into, you do not change the whole.

Try these:
6/10 + 2/10, 3/8 + 1/8, 3/9 + 4/9.

Unlike Denominators: To add with unlike denominators, you find a common denominator.
Once you find one, simply add the numerators of both the fractions to get your answer. 

For example,
4/12 + 1/4 = 7/12
1/4 can be changed into 3/12 by multiplying 1/4 by 3/3. 1/4 x 3/3 = 3/12. 
Re-write the question, 4/12 + 3/12 = 7/12. It's easier now, right? 

Try these:
5/7 + 2/14, 6/10 + 1/5, 2/6 + 1/3. 


Subtraction:

Like Denominators: To subtract fractions with like denominators, all you need to do is subtract the numerators. Then figure out your answer. It's the same with adding fractions with like denominators, except you subtract. 

For example, 
7/12 - 4/12 = 3/12  
Do not subtract denominators. (Because those are the equal pieces your whole is cut into, your whole does not change! As said before!)  

Try these:
14/20 - 8/20, 9/13 - 7/13, 4/5 - 3/5.

Unlike Denominators: To subtract fractions with unlike denominators, you have to find a common denominator. You can do it without finding a common denominator, but that would take more work. (E.g. Diagrams, etc.) 

For example, 
9/12 -  2/6 = 5/12 
You can change 2/6 into 4/12 by multiplying the fractions, 2/6 x 2/2 = 4/12. 
Then, re-write the question and simply subtract the numerators again for your answer. 
9/12 - 4/12 = 5/12 

Try these:
4/10 - 1/5, 7/16 - 2/8, 6/14 - 2/7. 

(Put answers into lowest terms if asked to. This applies to both adding and subtracting.)