The squid giant axon occupies a unique position in the history of our understanding of cell membrane potentials and nerve action.

The squid giant axon occupies a unique position in the history of our understanding of cell membrane potentials and nerve action. When an electrode is stuck into an intact giant axon, the membrane potential registers a negative number. Resting membrane potential at room temperature is solely determined by the sodium and potassium channels. See below for the ion gradients.
Ion Cytoplasm Seawater
Na+ 60 mM 420 mM
K+ 400 mM 20 mM
If the permeability to K+ is 50 times of that to Na+, what is the resting potential? (Show your work).
((im more so unsure of how to represent K+ increase in permeability (50 times more) relative to NA+. Do i simply assume Na+ is 1 and K+ 50 or do i write it as a decimal and if so how? Or am i supposed to use their normal known permeabilities and calculate the percentage from that somehow.
Thankyou for your help