Dividing both sides by 86 leads you to [tex] \frac{16}{86} = 0.83^{x} [/tex] which is equal to [tex] 0.1927 = 0.83^{x} [/tex]
Then, all you have to do is take natural logarithm both sides: [tex]ln (0.1927) = x ln (0.83)[/tex] which is a result of applying natural logarithm properties (particulary the property that affirms that [tex]ln (m^n) = n \plus {ln(m)}[/tex])
