Question 210935
A vendor has learned that by pricing hot dogs at $1.00, sales will reach 135 hot dogs per day. 
Raising the price to $1.60 causes sales to fall to 105 hot dogs per day. 
Let y be the number of hot dogs the vendor sells when they're priced at x dollars. 
Write a linear equation that models sales as a function of price.
:
Guidelines:
1. What two 'points' (x-value, y-value pairs) are we given?
x1 = 1.00; y1 = 135
x2 = 1.60; y2 = 105
:
2. What is the slope of the line connecting these points?
The slope formula: m = {{{(y2-y1)/(x2-x1)}}}
m = {{{(105-135)/(1.6-1)}}} = {{{(-30)/.6}}} = -50 is the slope
:
3. Use the formula:
y – {some point's y-value} = m * ( x - {some point's x-value} ) to derive the equation
(note: some point's y-value and some point's x-value must be the respective x and y values of the same point)
:
y - 135 = -50(x - 1) 
y - 135 = -50x + 50
y = -50x + 50 + 135
y = -50x + 185