How do you add and subtract fractions?

Question

Please tell me.

Answer 1

You have to find a common denomonator. You must have learned about "least common multiples."

So, if you're adding 2/5 + 1/4, the least common multiple (lowest number both of these can go into) of these two numbers is 20.

2/5 = 8/20 because 5 goes into 20 four times, then you multiply the numerator by 4 and get 8

1/4 = 5/20 because 4 goes into 20 five times, then you multiply the numerator by 5

8/20 + 5/20 = 13/20 This can't be reduced any lower. But to reduce, you look for the "greatest common factor" (highest number that can be divided into each of these numbers evenly). Good luck.

Answer 2

Remember to NEVER add or subtract the denominators.

For example: 1\6 - 1\2 is NOT equal to 1\4

Answer 3

If they have the same denominators (numbers on the bottom), then just add/subtract the numerators (numbers on the top.) Your final answer will be the sum of all the numerators over the common denominator.

If they have different denominators, multiply the numerator of each fraction by the denominators of all of the other fraction, then add/subtract them. You final answer will be the sum of all those numbers over the product you get when multiplying all of the denominators together.

Answer 4

1. Find a common denominator for the fractions
2. Follow the indicated operation and solve the problem
3. example:

2/5 +1/4=
1. use 20 as the lcd
since 5 goes into 20 4 times - the numerator and denominator are both 4
2/5 * 4/4=8/20

1/4 4 goes into 20 5 times so numerator and denominator are both 5
1/4=5/20

Follow the operation
8/20+5/20=13/20

Answer 5

you make sure the denominators match by using common multiple factors and then you times the numerator by how much you timed the denominators by to make them match then you either add or subtract than simplify example:

2/4+2/8
4/8+2/8=6/8
3/4

5/6- 2/4
20/24-12/24
8/24
1/3

Answer 6

you need to make the denominators the same. example: 3/4 + 2/3 = ?

you make 3/4 into 9/12 and 2/3 into 8/12. 9/12 + 8/12 = 17/12

17/12 = 1 5/12

subtraction: 9/12 - 8/12 = 1/12


hope that helps!

Answer 7

You need to make the denominators the same.
ie: 1/2-1/4
= 2/4-1/4
= 1/4

Answer 8

Hope This Helps!!!

Answer 9

you add and subtract.