Isaac Physics - Drift Velocity (A level)

Question: https://isaacphysics.org/questions/drift_velocity?board=afdee795-5859-4642-88ac-ddfc914c5482&stage=a_level

I've combined i=nAev, V=IR and R=pl/A to get:
v = V/nepl
where v = the drift velocity, V = potential differnce, e= charge of electron, p = resistvitiy and l = length

I know I need to use the Avogadro's constant and density to find the number density somehow, but im struggling to work out how to do this and keep getting the wrong answers. Could someone help me do this?