Question

What is the difference (in mV) between the membrane potential at rest versus the threshold potential in an axon?

Answer 1

In fact, your extent is right yet the sign isn't right. Inconsistent life, contrasts are constantly positive.
Additionally, on the off chance that we do stick to math rather than regular use, the distinction between the resting layer potential (- 70mV) and the edge potential (- 55mV) would be - 55mV - (- 70mV) = 15mV.