The following equations represent the demand and supply for bottles of nail polish.
Qᴰ = 25 - P
Qˢ = -15 + 3P
What is the equilibrium price (P)and quantity (Q - in thousands)of bottles of nail polish?
A)P = $5; Q = 20 thousand
B)P = $15; Q = 30 thousand
C)P = $20; Q = 5 thousand
D)P = $10; Q = 15 thousand

Question

Quizplus · Accepted Answer

To find the equilibrium price and quantity we need to set quantity demanded equal to quantity supplied and solve for P. 
Qᴰ = Qˢ 
25 - P = -15 + 3P 
Solving for P: 
4P = 40 
P = $10 
Substituting P back into either the demand or supply equation to solve for Q: 
Q = 25 - P = 25 - 10 = 15 thousand
So, the equilibrium price is $10 and the equilibrium quantity is 15 thousand bottles of nail polish. Therefore, the answer is D.

The Following Equations Represent the Demand and Supply for Bottles