what’s the answer to 1/2b-3/4-5/15?

Question

Simplify the expression

Answer 1

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

Comments

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

Answer 2

 

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 = 2²∙3¹ = 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.

Comments

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.