Answer:
B
Step-by-step explanation:
[tex]5\cdot 21^{5x} = 16 \\\ 21^{5x} = \frac{16}{5} \\\\ 21^{5x} = 3.2 \\\ log 21^{5x} = log 3.2 \\\ 5x\cdot log 21 = log 3.2 \\\ 5x = \frac{log 3.2}{log 21} \\\\\ x = \frac{log 3.2}{5\cdot log 21}[/tex]
I hope I helped you.
