Question

If the equation for the demand curve is Q=45-2p and the equation for the supply curve is Q=-21+4p then the equilibrium values for price and quantity are?

Answer 1

$Q$_d $=45-2p$

$Q$_s $= -21+4p$

At equilibrium $Q$_d $=Q$_s

$45-2p=-21+4p$

$45+21=4p+2p$

$66= 6p$

$\frac{66}{6}$ $=\frac{6p}{6}$

$\therefore p=11$

$Q$_d $=45-2(11)$

Q_d $=$ $23$

At equilibrium the price is 11 and the equilibrium quantity is 23.