How to work a logarithm question

The general form is:

$$\log_b(y) = x \quad \iff \quad b^x = y$$

Example:
To solve $\log_2(8)$:
We are looking for the exponent $x$ such that $2^x = 8$.
Since $2^3 = 8$, then $\log_2(8) = 3$.