20 1/6 - 7 4/9= write in simplest form

Question

Need help with my daughters 6th grade math

Answer 1

Problem:

 

  20  1/6

-  7  4/9

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To add or subtract fractions, find a common denominator:

 

  20  3/18
-  7   8/18
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Now, you have to "borrow one" in order to subtract:

 

   19  21/18
 -  7    8/18
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  12  13/18       [this is simplest form]

 

Answer 2

20 1/6-7 4/9

find the least common denominator

6=2*3

9=3*3

LCD=3*3*2=18

or...

6,12,18

9,18

worst case you can multiply 6*9=54 for a common denominator but you will have to simplify the answer after you finish the problem

1/6=3/18

4/9=8/18

20 3/18-7 8/18

you can't subtract 8 from 3

borrow 1 from 20 and call it 18/18

add 18/18 to 3/18 to get 21/18

now you have 19 21/18-7 8/18=12 13/18