Question

Evaluate 4 over 7 - 7 over 15 + 1 over 3

Answer 1

confusing or not, that is what you have to do

Answer 2

These are fractions

Answer 3

yeah i know
lets take them one at a time

Answer 4

\[\frac{4}{7}-\frac{7}{15}\] is the first one

Answer 5

Ops the first one is 4/5

Answer 6

4/5 - 7/15 + 1/3 ?

Answer 7

Yaa

Answer 8

then it is easier

Answer 9

Be right back sorry

Answer 10

It's so simple..
4/5 = 12/15 ? Understood.
1/3 = 5/15 ?understood.
The answer is 12/15+5/15 - 7/15 = 10/15 = 2/3

Answer 11

I don't get it @vipvipindev

Answer 12

Understood 4/5 = 12/15 ?

Answer 13

Noo

Answer 14

How.... it is bc you simply that to get 4/5

Answer 15

4/5 *3/3=12/15

Answer 16

For addition we require a need to make the denominator same. So by multiplying 5 with 3 we get it as 15. When we multiply to denominator we also do it for numerator. Understood?

Answer 17

Ohokkk yes

Answer 18

Sameway did here : 1/3* 5/5 ?

Answer 19

\[\frac{ 4 }{ 7 }-\frac{7}{15}+\frac{1}{3}\]
Find the common factor of the denominators:
7: 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98, 105
15: 15, 30, 45, 60, 75, 90, 105
3: 3, 6, 9, 12, 15, ... , 105 (because 3 x 35 = 105)

Multiply the fractions to make the numerator the same as the common factor:
\[\frac{ 4 }{ 7} * 15 = \frac{ 60 }{ 105 }\]
\[\frac{ 7 }{ 15} * 7 = \frac{ 49 }{ 105 }\]
\[\frac{ 1 }{ 3} * 35 = \frac{ 35 }{ 105 }\]

Lastly, add/subtract the fractions with the same denominator:
\[\frac{ 60 }{105}-\frac{49}{105}+\frac{35}{105} =\frac{46}{105}\]

Answer 20

So u have to get he the nominator to all be the same

Answer 21

Denominator **

Answer 22

Yes that is correct

Answer 23

Argilly showed the whole process for the problem as originally posted

Answer 24

But it says the answer is 2/3

Answer 25

Key is to find the common denominator. One way is to just multiply all of the denominators together. This works, but gives a bigger number than neede if one denominators is a multiple of another.

Answer 26

I think it's better to give 15 as a common denominator so that he/she can understand!@whpalmer4

Answer 27

Ohokkkkkk I get it now ... but vipvipindev if e denominator is 15 how did u get 3

Answer 28

\[\frac{4}{5}-\frac{7}{15}+\frac{1}{3}=\frac{4*3}{5*3}-\frac{7}{15}+\frac{1*5}{3*5}=\frac{12-7+5}{15}=\frac{10}{15}=\frac{2*5}{3*5}=\frac{2}{3}\]

Answer 29

@vip hadn't finished yet, doing latex on iPad keyboard while walking is very slow...

Answer 30

You can also find least common multiple to use as common denominator by making lists of multiples to see which comes up first:

3 6 9 12 15
5 10 15
15

15 is first number to appear in all 3 lists so it is least common multiple of 3,5,15

Answer 31

Ohhh okk I see now...thanks you

Answer 32

Can also do it by factoring denominators and combining

3 factors to 3
5 factors to 5
15 factors to 3*5

We multiply each unique factor found, using as many copies found in the number that had the most. Here that would be 3*5=15

Answer 33

I get it now wow that was easy now that I noe it

Answer 34

If doing problem with different denominators of 2 8 12 (for example only)

2: 2
8: 2*2*2
12:2*2*3

Here we multiply 2*2*2*3=24 because 2 and 3 were factors found and we had 3 2s in factors for 8

2 4 6 8 10 12 14 16 18 20 22 24
8 16 24
12 24

Again 24 is first number in each list so it is least common multiple of 2,8,12

This example shows how just multiplying denominators together may give unnecessarily large denominator: 2*8*12=192 which is 8x as big as needed!