Question

-1/12 - 3/4 =
A. -1/3
B. -5/6
C. 2/3
D. -4/16

Answer 1

can you find the common denominator?

Answer 2

4

Answer 3

for 12 list out its multiples: 12,24,36
for 4: 4,8,12,16,20
look for a number on both lists

Answer 4

This might help you
http://www.khanacademy.org/math/arithmetic/fractions/v/adding-fractions-with-unlike-denominators

Answer 5

As phi said, both 4 and 12 have a common multiple of 12.
4 multiplied by 3 equals 12, so multiply the numerator(3) by 3 as well.


\[\frac{ -1 }{ 12 } *1 = \frac{ -1 }{ 12 }\]\[\frac{ 3 }{ 4 } *3 = \frac{ 9 }{ 12 }\]

Now find the difference of the numerators:
\[\frac{ -1 }{ 12 } - \frac{ 9 }{ 12 } = \frac{ (-1) - 9 }{ 12}\]