adding subtracting with different denominators

Adding Subtracting Adding Subtracting with Different with Different DenominatorsDenominators

By KCBy KC

2/3 + 3/9

To find the answer you have to find the LCM. The LCM is 9 because 3X3 equals 9. You times the 3X3 so you have to times number 2 by 3, so you get 6/9 + 3/9.

3/9 + 6/9

9/9 =1

I got an answer of 1 out of 2/3 + 3/9. I got the answer 1 because you times 3x3 to get LCM. When you have got the LCM, you have to times 2 by 3 so it becomes 3/9 + 6/9. When you have the LCM you just add the top number and keep the bottom number same.

5/10 - 3/20

To find the answer you have to find the LCM. The LCM is 20 because 10X2 equals to 20. You have to time 10by2 because you need to get LCM, so it is 10/20-3/20.

10/20 – 3/20

= 7/20

I got 7/20 for an answer from 5/10 - 3/20because you times 10 by 2 so you can get a LCM. Then you have to times 5 by 2 because you had multiplied 10 by 2. After you get the LCM you just subtract the top number and the keep the bottom number same.