Math Adding and subtracting fractions?

Answers are only useful once, so it will be more help to you if you try to understand and remember methods for future use. Please only copy down the answer when you are sure you really understand.

Look at the lower numbers in each fraction, (denominators). They are:-

4 which is 2*2 and

18 which is 2*3*3 and

12 which is 2*2*3

Hopefully you can see that a number which is 2*2*3*3 = 36 "contains" all the others.

To explain what I mean, 36 = 4*9 = 2*18 = 3*12

The number 36 which contains all the other denominators is called the common denominator.

The method of adding and subtracting fractions relies on expressing each fraction in terms of the common denominator. First see if you can understand each fraction in terms of 36ths like this.

3/4 = 3*9/36 = 27/36

11/18 = 11*2/36 = 22/36

1/12 = 3/36

Using those results you work out the answer like this.

3/4 + 11/18 - 1/12 = (27 + 22 - 3)/36 = 46/36

That is one form of answer but it is not in its simplest form because we can divide top and bottom by 2, so the answer is 23/18.

This can also be written as 1 and 5/18

Regards - Ian H

Let's get the answer first. It is either 1 and 5/18 or 23 / 18

First find the common denominator

4 factors down to 2 * 2

18 factors down to 3 * 3 * 2

12 factors down to 2 * 2 * 3

the lowest common denominator will two 2s in it and 2 threes

2 * 2 * 3 * 3 = 36

3/4 in 36ths is 3*9 / 4*9 = 27 / 36

11/18 in 36ths is 2*11/2*18 = 22/36

1/12 in 36ths is 1*3/12*3 = 3 / 36

The result is

27 / 36 + 22 / 26 - 3 / 36 = (49 - 3) / 36 = 46 / 36 = 23 / 18

23 / 18 is an improper fraction which can be written as 1 with a remainder of 5 or 1 and 5/18

To calculate 3/4 + 11/18 - 1/12 use the commom denominator that is 36

Then it is so 27/36 + 22/36 - 3/36 = 46/36 = 23/18 OK!

Well,

you first have to find the common denominator

which, here, is 36 = 4 * 9 = 18 * 2 = 12 * 3

so

3/4+11/18-1/12 = 3*9/36 + 2*11/36 - 3*1/36

gives

3/4+11/18-1/12 = (27+22-3)/36 = 56/36 = 28/18 = 14/9

finally

3/4+11/18-1/12 = 14/9

hope it' ll help !!

3/4 + 11/18 - 1/12 is

27/36 + 22/36 - 3/36 =

49/36 - 3/36 =

46/36

or

1 10/36

which reduces to

1 5/18.

so we have 3/4+ 11/18-1/12

lets do the 3/4+11/18

multiply the denominators and we get 4x18 this equals 72 this is our new denominator

to get our new numerators we need to cross multiply

now we do 1st numerator x the 2 denominator and the 2nd numerator x the 1st denominator

so we do 3x18/72 + 4x11/72

we get 98/72 and we can divide both the numerator and denominator by 2

to get 49/36 in it's simpler form

now we can do 49/36- 1/12

36 x12= 432 that's our new denominator to get our new numerators we are going to cross multiply again

1st numerator x 2nd denominator and 2nd numerator x 1st denominator and subtract them in the end

so 49x12/432 - 1x36/432

this gives us 588/432- 36/432= 552/432

the numerator and denominator are both divisible by 24 so divide both by 24

we get 23/18 this is in its simplest form

theres your answer bobs ya uncle