Problem:

Which way and when to calculate the return of stock a ceratin way.

If you do the quotient rule, which is log(60/50) = log(60) - log(50) you get 0.079. I'm multiplying by 100 to turn it into a percentage (100 is not shares). (60-50)/50 = 0.2. Can you explain the difference in the percent differences? Doing it the log way gives you 7.92%, the arithmetic way is 20%. (I've heard that log relaxes the positive constraint, but to be honest I see people always finding the rate of return either way.) Show your all work and explain in detail.