Question 35467
{{{ log(b,M) = (ln M)/(ln b) }}}


This applies to any base of logarithms, not just to natural logarithms.

It also applies to log base 5, so

{{{ log(b,M) = (log(5,M))/(log(5,b)) }}}


You are asking 

{{{ log(8,M) = (log(5,7))/(log(5,8)) }}}, so therefore, M= 7.


R^2 at SCC