<em>It's nice of you to offer, but no thanks.</em>
To correctly graph this, you need to set up a simple equation and table of values. Luckily, this equation is dead-simple; I'll define <em>y</em> as the total cost and <em>x</em> as the number of water bottles sold.
Since 1.50$ is the cost for one bottle, multiplying that with your variable that defined the amount of bottles, <em>x</em>, gets you the total, <em>y</em>. Now that we have a basic equation, we can begin plugging in values.
Recall that a function is basically just something that takes in a value and returns another one; in our case, it takes the <em>amount of bottles</em> and returns the <em>total cost. </em>Now, plug in the x-values present on the graph (specifically only whole numbers, since you can't have a half bottle). I can't make a proper table but I'll make do.
x y
--------
0 0
1 1.5
2 3
3 4.5
4 6
5 7.5
-----------
Great, now that you have a table of values all you have to do is plug them into the graph, which I've attached. It's pretty crude since I drew it in mspaint but I'm sure you get the point at this point.
