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toc =Adding and Subtracting Fractions= Video: Professor Purifirfraction Teachs How to Add and Subtract Fractions

What is a Fraction
First of all you have to know what the fraction is, and what it represents.

--> Equals Numerator, the numerator represents the amount of pieces

--> Equals Denominator, the denominator represent the total amount of pieces

How To Add Fractions
To add a fraction, you have to have a question. For example 1/2 + 1/2 = ?. Think of it like bananas, if you have 1 banana, cut it into half, it will equal another 1/2. Then two of the halves added together will equal, one whole bananas. It should look like this: As you can see it shows 1/2 + 1/2 = 1.

But if its another question where the denominators are diffrent you have to remember two things: 1. Common Denominators 2. If the fractions are equivlent to something Common denominators are just denominators that go into each other easily without have to clash, and have a decimal point. Equivlent fractions mean the fractions are equal. For example, 1/2 is equivlent to 2/4. Although the denominators may be diffrent, they still equal the same thing. To add fractions with diffrent denominators you have to change the denominators, so that they are both the same denominator, and so it will be easier to add. For example: 1/2 + 1/3 You can write out all the numbers that both 2, and 3 go into. If you do it should look like this if you up to the first 10 numbers: From doing this you can see what numbers that 2 and 3 go evenly into. You can see they both go into 6, 12, 18, 24 and 30. You should pick the smallest number. Which is 6. Then 1/2 will equal 3/6, since you have to multiply it by 3, and 1/3 will equal 2/6 since you have to multiply it by 2. Another way to do this is multiply both denominators together. You have to multiply 2 and 3 together, to get 6 which is a quicker way. It should look like this: You can multiply the denominators and always get a denominator that both fractions go into, for example if you do 103/3432 + 234/3895, you will still be able to get a common denominator easily, if you multiply the denominators. After you do this, you know that you changed the question to equal 3/6 + 2/6. You just have to add the numerator together. You do not add the denominator togethers, or it will not equal the fraction you want. Finally you have to simplify the fraction. In this case you cannot simplify the fractions. But if the fraction answer is 4/12, you must simplify if to equal 1/3, to answer the question.

Word Problem
If Eddy plays basketball for 3 hours, ate all his meals in 6 hours, played video games for 4 hours, and was on the computer for 2 hours. He slept for the rest of the day. How long did he sleep out of the 24 hours of the day? The circle represents the amount of time he used for the whole day, you have to find how much time he was sleeping for.

How To Add Mixed Fractions
First of all you need to know what a mix fractions is: A mixed fraction is a whole number, and as well as a fraction. It looks like this: The one represents the whole number. While the one quarter represents the fractions. This would make it into a mixed fraction.

To add the mixed fractions for example, 1 1/4 + 1 1/7. You have to change the fractions into improper. Improper fractions should look like this: 10/8. For example. So when you change 1 1/4. You have to remember 1 is also equal to 4/4 + 1/4 = 5/4. Which is equivlent to 1 1/4. You do the same to 1 1/7. Which will end up being 8/7. So now you have to do what you would normally do to adding fractions. You would multiply the denominators. So it would be 4 times 7. Which would = 28. The denominator would equal 28. So you have to multiply 8 by 4 to get 32. And then you have to multiply 5 times 7. To get 35. So the question is now 35/28 + 32/28. You add up 32 + 35 to get 67. Then you place the denominator to get 67/28. So the answer is 67/28.

Subtracting Fractions
To subtract fractions, there are mainly the exact same step to adding fractions. Except you are subtracting instead of adding. You have to know about common denominators, and equivlent fractions. First you need an example: 8/9 - 2/7 = ? The first thing you can do is write down the first ten of the denominators common denominators. After doing this you can see that both numbers go into 63, and you can use that for a common denominator. Or you could have just multiplied both denominators to get a common denominator.

After this you have to do the exact same things you did to the bottom to the top. Since you multiplied /9 by /7. You have to multiply 8/ by /7, and 2/ by /9. So you get 56, and 18. So the new question you just made it is: 56/63 - 18/63. Right now is the easy part, you have to subtract the denominators together. 56 - 18 = 38. Then you have to place the denominator in, so the answer will equal, 38/63. Remember to simplify the fractions, although you can not do it in this question remember to do it in other questions you are able to simplify. Also fully answer the question, 8/9 - 2/7 = 38/63. Show all your work, because you never know when you can get extra marks, for showing all of it. media type="custom" key="846441"