Demand Supply Subsidy
1. **Stating the problem:** Given the demand function $P=36-4Q$ and the supply function $P=18+2Q$, we need to find:
(a) Equilibrium price and quantity before subsidy.
(b) New supply function after a subsidy of 6 units.
(c) Market equilibrium after subsidy.
(d) Shares of subsidy received by consumers and producers, and total government subsidy.
(e) Plot supply and demand curves before and after subsidy.
2. **Finding equilibrium before subsidy:**
Equilibrium occurs where demand equals supply:
$$36-4Q=18+2Q$$
Bring terms involving $Q$ together:
$$36-18=2Q+4Q$$
$$18=6Q$$
Divide both sides by 6:
$$Q=3$$
Find equilibrium price by plugging $Q$ into demand or supply:
$$P=36-4(3)=36-12=24$$
Equilibrium price $P=24$, quantity $Q=3$.
3. **New supply function after subsidy:**
A subsidy of 6 units reduces producers' effective cost by 6, so the price suppliers require is $P+6$ equal to original supply price.
Original supply:
$$P=18+2Q$$
With subsidy, suppliers accept price $P$ but receive $P+6$ effectively, so:
$$P+6=18+2Q$$
Solve for $P$:
$$P=18+2Q-6=12+2Q$$
New supply function is:
$$P=12+2Q$$
4. **Market equilibrium after subsidy:**
Find new equilibrium where demand equals new supply:
$$36-4Q=12+2Q$$
Bring $Q$ terms together:
$$36-12=2Q+4Q$$
$$24=6Q$$
Divide both sides:
$$Q=4$$
Find price by plugging $Q$ into new supply:
$$P=12+2(4)=12+8=20$$
New equilibrium price $P=20$, quantity $Q=4$.
5. **Subsidy shares and total subsidy:**
Before subsidy price was 24; after subsidy price is 20.
Consumers pay 20 instead of 24, so consumer gains subsidy portion of $24-20=4$ per unit.
Producers receive $20+6=26$ per unit, so producers gain $26-24=2$ per unit.
Total subsidy per unit is 6.
Total units sold after subsidy is 4, so total government subsidy is:
$$6 \times 4=24$$
6. **Summary:**
(a) Equilibrium before subsidy: $P=24$, $Q=3$.
(b) New supply: $P=12+2Q$.
(c) New equilibrium: $P=20$, $Q=4$.
(d) Consumer subsidy per unit: 4; producer subsidy per unit: 2; total subsidy: 24.
(e) See Desmos for supply and demand curves before and after subsidy.