Suppose a market research company finds that at a price (y) of $30, they would sell x =10 t-shirts. If they lower the price to y = $20, then more people would purchase the t-shirts, and they can expect to sell x = 30 t-shirts.

Question

Suppose a market research company finds that at a price (y) of $30, they would sell x =10  t-shirts. If they lower the price to y = $20, then more people would purchase the t-shirts, and they can expect to sell x = 30 t-shirts.

Find the equation of the line for the demand equation. Hint: Write your final answer in the form y = mx + b.  
(x , y) 
x =  quantity	y = price sold
10	30
30	20
(10, 30)	
(30, 20)

To get the equation for the line,

1.  First calculate   M =

2.  Use the point slope formula y - y = m(x - x ).  Use your slope (m) from step 1 along with one of your points and plug them into the point slope equation.  Write your final answer in the form y = mx + b.