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what’s the answer to 1/2b-3/4-5/15?

+1 vote
Simplify the expression
asked Mar 1, 2013 in PRE-ALGEBRA by Jose Rodriguez Rookie

2 Answers

+1 vote

1/2b-3/4-5/15

rewrite the fractions with common denominator

find least common multiple
multiples of 4 = 4, 8, 12, 16, 20, 24, 28, 32 , 36, 40, 44, 48 ,52, 56 ,60
multiples of 15 = 15, 30 ,45 ,60
Least common denominator is 60

=1/2b - 45/60-20/60

=1/2b - (45+20)/60

=12/b - 65/60

answered Mar 1, 2013 by kevin Rookie

The simplified form of 1/2 b - 3/4 - 5/15 is (6b - 13)/12.

+2 votes

 

The expressio is 1/2b - 3/4 - 5/15 -------> 1/2b - 3/4 - 1/3

Denominators are different, so find the least common denominator of 2, 3 and 4.
 

Write the prime factorization of each numnber.

2 =1∙2 = 21

3 = 1∙3 = 31

4 =2∙2 = 22

 

Multiply the highest power of each factor in either number..

LCM = 223= 12

Least common denominator is 12.
 
Rewrite the fractions with common denominator.
=6b/12 - 9/12 - 4/12.
=6b/12- (9 + 12)/12.
=6b/12 - 21/12.
=(6b - 21) / 12.
answered Mar 9, 2013 by steve Scholar

Rewrite the fractions with common denominator.

= 6b/12 - 9/12 - 4/12

= (6b - 9 - 4)/12

= (6b - 13)/12.

Therefore, 1/2 b - 3/4 - 5/15 = (6b - 13)/12.

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