Susan B. answered • 10/29/14
Tutor
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Hi Cindy,
You seem to be missing some information. Is there another plus sign between the last two fractions? I will assume there is.
The top number is called the numerator.
The bottom number is the denominator.
When adding fractions, you need to have all your denominators the same. When they are not the same, you work on them to get them all the same. You prepare them for addition. Here's what you do:
1 + 3 + 1 =
2 4 5
Look at your denominators, (bottom numbers) 2, 4, & 5.
Find the lowest whole number into which they will all divide (with no remainders).
Start with 5, the largest number.
10 ÷ 5 = 2 But 10 ÷ 4 = 2 1/2 So that won't work.
15 ÷ 5 = 3 But 15 ÷ 4 = 3 3/4 So that won't work.
20 ÷ 5 = 4 And 20 ÷ 4 = 5 And 20 ÷ 2 = 10 So this will work. :) Yay!!
So, to change our denominators to 20, we must also change our numerators (top numbers) as well. Like this:
Our original fractions are:
1 + 3 + 1 =
2 4 5
2 4 5
Preparing the first fraction: Whatever you do to the 2 to get it to 20, you must do the same to the 1. Multiply both the bottom and top number by 10.
2 * 10 = 20 And 1 * 10 = 10
Prepared fraction:
10
20
It is important you understand you have not really changed the fraction, you have stated it in different terms. It is exactly the same size.
1 = 10
2 20
Now prepare the second fraction in the same way. Multiply both the bottom and top number by 5 (the number that will get it to 20).
10 + 3 + 1 =
20 4 5
20 4 5
4 * 5 = 20 And 3 * 5 = 15
15
20
10 + 15 + 1 =
20 20 5
20 20 5
So now it is time to prepare the third fraction. Using the previous steps as an example, see if you can change it.
Remember, you want to change the denominator 5 to a 20, just like we did to the other fractions. But, don't forget to change the top number, as well. Whatever you do to the bottom number, you must do to the top number.
You can do it!!! :)
After you have prepared the third fraction ... and all of your denominators are the same, it is time to add. Only add the top numbers. Keep the bottom number the same. Here's an example:
5 + 7 + 3 = 15
45 45 45 45
Finally, take the answer and simplify it.
See if a number will easily divide into both the numerator and the denominator. In this case, it would be a 5.
15 ÷ 5 = 3 And 45 ÷ 5 = 9 So our fraction is:
3
9
We can simplify even more.
3 ÷ 3 = 1 And 9 ÷ 3 = 3 So our fraction is:
1
3
15 = 1
45 3
So our example answer is:
1
3
Were you able to use these steps to finish solving the original problem?
:)
