$$
\log_ab = x \Leftrightarrow   a^x = b 

$\displaystyle {a^{\log_ab} = b}$ 

$\displaystyle {\log _{a}b={\frac {\log _{c}b}{\log _{c}a}} }$

 ${\log _{a^{q}}{b}}^{p}={\frac {p}{q}}\log _{a}{b}$ 

$a^{\log_c b} = b^{\log_c a}$

$\displaystyle { \log_a b - \log_a c = \log _{a} \frac{b}{c} }$

$\displaystyle{ \log_2 76,8-\log_2 2,4 = \log_2 \frac{76,8}{2,4} = \log_2 32 = 5 }$

$2^5=2*2*2*2*2=32$