Solve Equation for n where n is the power ($3^n = \frac{1}{81}$)

Question

I have the equation: $$3^n = \frac{1}{81}$$

And I need to find n. Can someone explain how I do this, with steps please (GCSE level)?

TIA.

Answer 1

Use that $81 = 3^4$

Then $\frac{1}{3^4} = 3^n$

Then $n = -4$

Answer 2

After doing some googling I learnt that

$$ b^y = x \therefore log_b(x) = y $$

So then

$$ 3^n = \frac{1}{81} \therefore log_3(\frac{1}{81}) = n = -4 $$