I'm very stuck on question C and D can someone please explain it in detail and clearly!

Qd= 45-3P

Qs= 3P-9

Suppose the Aoslian government applies an import quota that limits imports to 12 bushels.

a) Determine the quantity demanded, quantity supplied, and new domestic price with the quota.

b) Calculate the quota rent.

c) Assuming that the quota licenses are allocated to domestic producers for free, what is the net effect of the quota on Aoslia's welfare?

d) Assuming that the quota rents are allocated to foreign exporters for free, what is the net effect of the quota on Aoslia's welfare?