Question 31882
Hello!
You can use the following rule of logarithms:

{{{log(x/y)=log(x)-log(y)}}}

So your equation becomes:

{{{160 = 20log (4/m)}}}
Divide by 20
{{{ 8 =log(4/m)}}}
Apply the log rule
{{{ 8 = log(4) - log(m)}}}
{{{log(m) = log(4)-8}}}
{{{ m = 10^(log(4)-8)}}}


I hope this helps!
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