Adding and Subtracting Fractions Help.. a little help please?

Question

Ok i finished high school like 4 moths ago but i did this stuff in like 8th grade so I kinda forgot =p, anyways this is for my sister she needs help and she just went into 8th grade. Thanks for the help my main bizzys =D I DONT REALLY CARE ABOUT THE ANSWER AS MUCH AS THE EXPLAINATION, DONT JUST GIVE ME THE ANSWER PLEASE I JUST NEED IT EXPLAINED IN STEPS.

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1/4+1/3=

3 3/4 + 1 1/5=

7/24 + 2 5/7=

5 2/7 - 2/3=

5/12- 1/3=

Answer 1

First of all I just finished 8th grade so I remember this stuff.

1/4+1/3=

Get the Least Common Multiple of 4 and 3. That is 12. Then multiply the one in both fractions times the number you multiplied 3 and 4 to get 12.

3/12+4/12=

Add them and you get the answer.

For subtracion you have to do the same thing to the denominators.

5/12-1/3=

Find LCM and multiply the numerator.

5/12-4/12=

Subtract and you have the answer. Also remember to subtract or add only the numerator not the denominator.

On 3 3/4+ 1 1/5=

3 15/20+1 4/20=

Figure it out.

Answer 2

Make both fractions the same common denominator. Like on the first one multiply the 1 and the 4 in 1/4 by 3 and you get 3/12 and the same thing on 1/3. Multiply them by 4 so they can both be 12. So they are common. 4/12. So your answer will be 7/12. Do the same on all of them.  

Answer 3

You have to find the common denominator for each of them. For the first one the common denominator is 12 cuz 12 fits in both 4 and 3.  

Answer 4

When you add/subtract fractions, the denominators (bottom part of fraction) must always be the same. If they aren't, you have to change it to be the same using LCD (Lowest Common Denominator).

1. 1/4 + 1/3 --> The LCD of 4 and 3 is 12.  

    So 1/4 becomes 3/12. (Because 4 times 3 equals 12 so since you multiply the denominator by 3 you must multiply the numerator by 3 too.)

And 1/3 becomes 4/12.

The new problem would be 3/12 + 4/12. Just add the numerators together and you get 7/12. So the answer to number 1 is 7/12.

2.  3 3/4 + 1 1/5

  Revised : 3 15/20 + 1 4/20

  Ans: 4 19/20

Try solving the rest by yourself using the same technique.