partial derivative and the chain rule

Hi all. I had a question concerning a problem my professor has given me, and i'm stuck and how to approach this problem. I have searched online for awhile now looking for similar problems, but i have come up empty. You all seem to know what you're doing and i was hoping that maybe you could point me in the right direction. Thanks for all your help in advance.

If z=f(x,y), x=g(t), y=h(t), g(3)=2, g’(3)=5, h(3)=7, h’(3)=-4,

fx(2,7)=6 and fy(2,7)=-8 then find dz/dt at t=3. Write out the chain rule __and__ intermediate steps.