Question

1) Equilibruim price: You can sell 280 products per week if they are marked at $15 each, but only 240 each week if they are marked at $18 each. Your supplier is prepared to sell you 320 products each week if they are marked at $20 each and 220 each week if they are marked $12 each. Find the demand equation, supply equation and equilibrium price for this product, using variables P for sales piece and Q for sales quantity.

Now I NEED TO KNOW HOW TO DO IT AND I KNOW THE ANSWERS
Demand equation: q=-13.33p+480
Supply equation: 12.5p+70
Equilibrium Price: $15.87
I know how to get -13.33p but...

Answer 1

formula for demand is q=mp+b
and I cant remember supply's formula :$
I need to know how to get B

Answer 2

And to get m i used x2-x1/y2-y1

Answer 3

treat both the supply and demand equation like linear equations of the form:
y=mx+b
where quantity is y, and price is x

Answer 4

so both have the same linear equation? right?

Answer 5

but how do i get b?

Answer 6

once you have the slope substitute in a quantity and its price to find the constant aka y -intercept

Answer 7

I remember i took a price from the both demand prices and then i used the formula but i cant seem to pull it off :/

Answer 8

then set them equal to each other and solve for the price

Answer 9

uhm... I dont get it...srry but can you make B?

Answer 10

use the point when the price is 15 dollars and the quantity demand is 280
280=15*-13.33+B
B=280+200
B=480

Answer 11

oh god thnx
by any chance do you know the equilibrium price formula?

Answer 12

set the demand equation equal to the supply equation
-13.33p+480=12.5p+70, solve for p

Answer 13

ok thnx you are a life saver, i gave you a medal ;D

Answer 14

thanks :)

Answer 15

I may ask later another question in like 10 min if you have the time