stuff

The ratio between voltage potential difference and current will be equal to resistance, assuming the circuit is ohmic.

Therefore, we can calculate current with the following equation:

$R=\frac{V}{I}$

Where R is resistance, V is potential difference, and I is current.

In your question's case we would use it as shown:

$220=\frac{9}{I}$

$I=\frac{9}{220}$

$I=0.041A$

(Please don't call it voltage. Volts are the units of potential difference. It's like calling distance "meterage" or time "secondage".)