Math
posted by Terri .
The quantity demanded each month of russo Espresso Makers is 250 when the unit price is $140; the quantity demanded each month is 1000 when th e unit price is $110. the suppliers will market 750 expresso makers if the unit price is $60 or higher. At a unit price of $80 they are willing to market 2250 units Both the demand and supply equations are known to be liniear.
A: Find the demand equation.
B: Find the supply equation.
C: Find the equilibrium quantity and the equilibrium price.

demand:
(d250)/(p140) = (1000250)/(110140)
d250 = 25(p140)
d = 25p + 3750
supply:
(s750)/(p60) = (2250750)/(8060)
s750 = 75(p60)
s = 75p  3750
equilibrium:
25p + 3750 = 75p  3750
100p = 7500
p = 75
s = d = 1875