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fractions calculations add and subtract 4

problem: fractions calculations add and subtract 4


Determine the lowest common denominator and calculate the value, reduce the solution and write as a mixed fractions if possible! 
 
8/15 + 5/18 – 7/10 =
 
 

answer: fractions calculations add and subtract 4


the lowest common denominator:

15 = 3 * 5 

18 = 2 * 3 * 3 

10 = 2 * 5 

2 * 3 * 3 * 5 = 90

 

to make the bottom numbers the same you have to multiply the top and the bottom of 

the first fraction with 6    (because  15 * 6 = 90) 

the second fraction with 5  (because  18 * 5 = 90) 

the third fraction with 9   (because 10 * 9 = 90) 

 
 
calculate the value:
 
8*6/15*6 + 5*5/18*5 – 7*9/10*9 =
 
48/90 + 25/90  63/90 =
 
73/90  63/90  = 10/90
 
 
simplify the solution with 10:
 
10:10/90:10 =  1/9