Question

Assume that the situation described can be modeled by a linear equation. Use the given information to find the y=mx+b form of the equation of the line. Suppose that a sales person observes that if an item is priced at $4 per item then 11 items are sold. If 9 items are sold for $6 per item then find an equation to model the number y of items sold for x dollars per item.

Answer 1

slope (m) = (9-11)/(6-4) = -1
so, y=-x+b
y(4)=11, so b=15

y = -x+15