This particular integral is driving me crazy. I can't figure it out for the life of me. Could someone please explain to me how to go about solving it?

Integrate[5x(7x - 9)^14dx

I was given a few hints but they still are not helping me at all. First let U=7x-9 and then let x=(U+9)/7. I would imagine this should be done using the substitution method. Thanks in advance

John