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fractions calculations add and subtract 1

problem: fractions calculations add and subtract 1


Determine the lowest common denominator and calculate the value, reduce the solution and write as a mixed fractions if possible! 
 
3/4 + 2/5 – 9/10 =
 

answer: fractions calculations add and subtract 1


the lowest common denominator:

4 = 2 * 2      

5 = 1  * 5 

10 = 2 * 5 

2 * 2 * 5 = 20

 

calculate the value:

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

the first fraction with 5    (because  4 * 5 = 20) 

the second fraction with 4  (because  5 * 4 = 20) 

the third fraction with 2   (because 10 * 2 = 20) 

 
3/4 + 2/5  9/10  =
 
3*5/4*5 + 2*4/5*4  9*2/10*2 =
 
15/20 + 8/2 18/2=  
 
23/20   18/2 5/20  
 
simplify the solution with 5:
 
5:5/20:5 =  1/4