Easy question on stochastic process

[grossgermany]

Suppose that A and B follow geometric brownian motion, where zA, and zB follow wiener process
dA/A=a*dt+b*dzA
dB/B=c*dt+d*dzB
dzA*dzB=e*dt
What stochastic process does A/B follow?

This is not a homework question(I am sure it's almost trivially easy to those who learned the stuff). I am very new to the stuff and would anyone be kind enough to show me the result and derivation?

I have browsed through textbooks yet none of them have a similar example.

 

[rochfor1]

Try looking up Ito's Formula.