Question

How do u work this 9/10 -2/5

Answer 1

First you have to have like denominators in order to subtract or add fractions. Do you know how to do that?

Answer 2

This video might help you
http://www.khanacademy.org/math/arithmetic/fractions/v/equivalent-fractions

Answer 3

And this one, after you watch the first one
http://www.khanacademy.org/math/arithmetic/fractions/v/adding-fractions-with-unlike-denominators

Answer 4

do u have one for subtracting?

Answer 5

http://www.khanacademy.org/math/arithmetic/fractions/v/adding-and-subtracting-fractions
I think that's it

Answer 6

\[\frac9{10} -\frac25 =\frac9{10} -\frac{2\times2}{2\times5}=\frac9{10}-\frac{4}{10}\]