Hello!
Let's take this problem
2/7+3/14+4/7
First we need all common denominators. So we need to times the two 7s into 14
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So it should look like 4/14+3/14+8/14
Since they all have common denominators now, we are able to add all the top numbers
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4+3+8 = 15
15/14
You can have the option of two final answers 15/14 OR 1 1/14. (Your able to take out a one, with a remainder of 1/14)
Let me know if you don't understand! Hope this helps!