If $log_4$ x = 12, then $log_2$ (x / 4) = ?

Explanation

B) 22. From $log_4$ x = 12, x = $4^{12}$ = $2^{24}$. Then x/4 = $2^{24}$ ÷ $2^2$ = $2^{22}$, so $log_2$ (x/4) = 22. A quicker route: $log_2$ x is twice $log_4$ x, so it is 24, and dividing by 4 takes away $log_2$ 4 = 2.