Subsidy answer

200-P=20+2P so P=60 and Q=140

with subsidy of $15... 200-P= 20+2(P+15).... SO P=50 Q= 150

COST TO GOV= SUBSIDY PER UNIT (15) X Q 150= 2250

Change in CONSUMER SURPLUS=(60-50)x140=1400 +0.5x 10x10=50 so total change is 1450

Increase in Producer surplus (be careful)= (5x140) + 0.5x5x10=725

So welfare loss= 2250- (1450+725)=75

Revenue for firm= 65x150=9750

Spending by consumers=150x50=7500

PED=0.43