I need to isolate the variable n (years) from this equation:

Pt = Po * (1 + {GR/100})^n

I tried using logs:

log Pt = log Po * n log (1 + {GR/100})

then I tried n = _________log Pt_________

log Po * log (1 + {GR/100})

Dows anyone know where I am going wrong? Its been ages since i've used logs.