# Thread: How would i do this work out?

1. ## How would i do this work out?

I need the break down on how to get the answer please.

8 21/22+3/4-5/12=?

The eight is a mix number with twenty one and twenty two

2. Originally Posted by Math Noob
I need the break down on how to get the answer please.

8 21/22+3/4-5/12=?

The eight is a mix number with twenty one and twenty two
Im not sure what the 8 is doing there, but let's pretend that it isnt because the idea is the same.

You need to find a common denominator here...

Do you know how?

3. the eight is the whole number of 8 21/22

you have to multiply 22 by 8 and then add the 21 correct?

i got that part figured out now what's next? find the common denominator of each fraction?

4. Originally Posted by Math Noob
I need the break down on how to get the answer please.

8 21/22+3/4-5/12=?

The eight is a mix number with twenty one and twenty two
$8\frac{21}{22} + \frac{3}{4} - \frac{5}{12}$

Find the LCM of 22, 4 and 12 which is 132 also that 8 can also be written as $\frac{8 \times 22}{22}$

5. Originally Posted by Math Noob
the eight is the whole number of 8 21/22

you have to multiply 22 by 8 and then add the 21 correct?
Correct! Sorry that I didn't notice that, by the way. So we will have...

$\frac{176}{22}$

So, now what should we do? The common denominator, right.

6. how did you find the common denominator so fast?

7. Originally Posted by Math Noob
how did you find the common denominator so fast?
Using prime factors.

22 = 2 x 11
12 = 2 x 2 x 3

Multiply any unique prime factors: 2 x 2 x 3 from 12 and 11 from 22:

$2 \times 2 \times 3 \times 11 = 132$

8. Originally Posted by Math Noob
how did you find the common denominator so fast?
I will stand down now.

9. lol im still trying to figure it out

10. the answer is 9 19/66

11. Originally Posted by Math Noob
lol im still trying to figure it out
$\frac{197}{22} + \frac{3}{4} - \frac{5}{12}$

As this does not ask for the LCM you don't need to use it - you can cross multiply if you wish

I don't see why you don't number crunch it?

12. because i am a noob, and would love to know how to number crunch

13. By using a calculator and putting in the numbers

$\frac{197}{22} + \frac{9}{12} - \frac{5}{12}$

LCM is 132

$
(\frac{197}{22} \times \frac{6}{6}) + (\frac{9}{12} \times \frac{11}{11}) - (\frac{5}{12} \times \frac{11}{11})$

$= \frac{1182}{132} + \frac{99}{132} - \frac{55}{132}$

$= \frac{1182+99-55}{132}$