How much work is done in moving a charge of 3 C across two points having a potential difference of 12 V?

Potential difference = 12 V
Charge = 3 C
Work done =?

We know that electric potential difference is defined as the work done in bringing unit charge from one point to another. 

$\mathrm{Potential} \mathrm{difference}\left(\mathrm{V}\right) = \frac{\mathrm{Work} \mathrm{done}\left(\mathrm{W}\right)}{\mathrm{charge}\left(\mathrm{Q}\right)}$

$\mathrm{W} = \mathrm{V} \times \mathrm{Q}$
$\mathrm{W} = 12 \mathrm{V} \times 3 \mathrm{C}$
$\mathrm{W} = 36 \mathrm{J}$

Therefore, the amount of work W, done in moving the charge is 36 J.