The inverse demand function for eggs is p = 84

Question

The inverse demand function for eggs is p = 84 - 9q, where q is the number of cases of eggs.The inverse supply is p = 7 + 2q.In the past, eggs were not taxed, but now a tax of 33 dollars per case has been introduced.What is the effect of the tax on the quantity of eggs supplied?
A)Quantity drops by 2 cases.
B)Quantity drops by 3 cases.
C)Quantity drops by 6 cases.
D)Quantity drops by 4 cases.
E)None of the above.

Quizplus · Accepted Answer

The new price paid by consumers, including the tax, is p = F1F1F1S1F1F1F10 84 F1F1F1S1F1F1F10 9q + 33. 
Setting that equal to the supply equation, we get: F1F1F10 84 F1F1F1S1F1F1F10 9q + 33 = F1F1F10 7 F1F1F1S1F1F1F10 2q
Simplifying that expression gives: 
126F1F1F1S1- 18q= 231F1F1F10 -33
Rearranging and solving for q yields:
q = 3. Considering that the original quantity supplied was q=5, the effect of the tax is a decrease of 2 cases. Therefore, the answer is (B) Quantity drops by 3 cases.