Question 1037913
this would be a straight line equation.
the slope intercept form of a straight line equation is:
y = mx + b
m is the slope
b is the y-intercept.


let x = the number of miles.
let y = the cost for that number of miles.


you have 2 points.


(x1,y1) = (10,17.50)
(x2,y2) = (20,30)


the slope of a straight line equation is equalt to (y2-y1)/(x2-x1)


that would be (30-17.50)/(20-10)


simplify that to get slope = 12.50/10 = 1.25


your equation of y = mx + b becomes y = 1.25*x + b


now use one of the points to solve for b.


you replace x with the x-coordinate of one of the points and you replace y with the y-coordinate of that same point and then solve for b.


y = 1.25x + b becomes 30 = 1.25*20 + b when you use the point (20,30).


solve for b to get b = 30 - 1.25*20.


simplify to get b = 30 - 25.


combine like terms to get b = 5.


your equation is y = 1.25*x+5


what this equation says is that you will pay 5 dollars to get into the cab and then you will pay 1 dollar and 25 cents for each mile that the cab takes you.


for example:


to go 10 miles, the cost is 5 dollars plus 1.25 * 10 = 5 dollars + 12.5 = 17 dollars and 50 cents.


to go 20 miles, the cost is 5 dollars plus 1.25 * 20 = 5 dollars plus 25 dollars = 30 dollars.


the graph shows that to you.
x represents the number of miles.
y represents the cost to go that number of miles.


the graph is shown below:


<img src= "http://theo.x10hosting.com/2016/061201.jpg" alt="$$$" </>