How does one go from:

(2x)^(9-k) (3/x)^k

to...

2^(9-k) 3^k x^(9-2k)

???

I'm sure it's an easy year 8 level problem, But I have not worked with fractions for a long time and seem to have forgotten it!

Thanks in advance!

PS:

For anyone actually interested in the binomial question, it is as follows:

Find the coefficient of x in the expansion of (2x + 3/x)^9

I have the answer if anyone wants it, I just don't understand the fractions part which I asked about above.