I guess the answer is $9.
At equilibrium, Qd=Qs
Therefore, 64-16P=16P-8
Or, 32P=72 or, P=72/32=$2.25
At equilibrium, Qd=Qs=28.
If government restricts quantity to 16 units then it will create deadweight loss to the market.
If quantity=16,
Qd=16=64-16P or, Pdemand= 3
Demand price is $3 at this fixed quantity=16 Similarly, Qs=16=16P-8 or, Psupply= $1.5
At this quantity, supply price is $1.5
So, deadweight loss= loss in consumer surplus+ loss in producers surplus
={(1/2)*(28-16)*(3-2.25)} + {(1/2)*(28-16)*(2.25-1.5)}
= (4.5+4.5)=9
Therefore, loss equals $9.