Hmm.

I'm assuming that says the following:

[(x^2 + 4x - 21)/(x^2 - 6x - 16)]*[(x^2 - 8x + 15)/(x^2 + 9x + 14)]

Factor:

x^2 + 4x - 21 = (x - 3)*(x + 7)

x^2 - 6x - 16 = (x - 8)*(x + 2)

x^2 - 8x + 15 = (x - 5)*(x - 3)

x^2 + 9x + 14 = (x + 2)*(x + 7)

Are you able to take it from here?