Reduce the fraction to simplest form

I'm stuck on this question.

x^2 - 4y^2
--------------------------------
3x^2 + 7xy + 2y^2

factor top and bottom as

top: (x-2y)(x+2y)
bottom: (x+2y)(3x+y)

so the x +2y cancels and you get the answer of (x-2y)/(3x+y)