Suppose a market research company finds that at a price of p = $20, they would sell x = 42 tiles each month. If they lower the price to p = $10, then more people would purchase the tile, and they can expect to sell x = 52 tiles in a month’s time. Find the equation of the line for the demand equation.

(42,20),(52,10) are two points.

slope of the line m=(10-20)/(52-42) =-1.

y-y1=m(x-x1).

y-20=-1(x-42).

y-20=-x+42

y=-x+42+20.

y=-x+62.