We are given x represent the number of pencils purchased, and let y represent the total cost.
We also given 18 pencils for $4.50.
Therefore, cost of each pencil = 4.50/18 = $0.25
Total cost (y) = cost of each pencil × number of pencils.
Therefore, equation would be
<h3>y = 0.25x.</h3>
In order to graph it, let us find some points for graph using table.
Plugging x=4, we get
y = 0.25(4) = 1.
Plugging x=8, we get
y = 0.25(8) = 2.
<h3>We got two coordinates, (4,1) and (8,2).</h3>
Plotting those points on the graph and joining the points.
We can see that graph represents the proportional relationship.