[tex]\bf \textit{exponential form of a logarithm}\\\\
log_{{ a}}{{ b}}=y \implies {{ a}}^y={{ b}}\\\\
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%2800=1900(1+0.025)^n into a logarithm
2800=1900(1+0.025)^n\implies \cfrac{2800}{1900}=(1.025)^n\implies \cfrac{28}{19}=1.025^n
\\\\\\
\begin{cases}
a=1.025\\
b=\frac{28}{19}\\
\end{cases}\implies log_{1.025}\left( \frac{28}{19} \right)=n[/tex]