Simple Linear Equation?

1. Jul 8, 2010

vitaminZ

1. The problem statement, all variables and given/known data
P = -50Qd + 80
P = 2Qs + 10

P = Price
Qd = Quantity demanded
Qs = Quantity supplied

Find the equilibrium Price and Quantity.

2. Relevant equations
Qd = Qs
(equilibrium)

3. The attempt at a solution
Qd = Qs
Q

Since they both equal to P

-50Q + 80 = 2Q + 10 [-2Q]
-52Q + 80 = 10 [-80]
-52Q = -70 [/52Q]
Q = 70/52
Equilibrium Quantity = 70/52

I don't know why this is wrong?

2. Jul 8, 2010

TxRationalist

I came up with the same answer. I didn't major in economics, though...I just assumed (because it sounds right) that you are right, that equilibrium occurs when the supply = demand.

3. Jul 8, 2010

Staff: Mentor

Are you sure that you are starting with the right equations? Have you given the problem exactly as it appears in your text or wherever you got it? I'm especially concerned with your Qd equation with the -50 coefficient.

4. Jul 22, 2010

utkarsh009

are you sure that this equation has 2Qs or should it have 20Qs.