Question

Braden bought 18 pencils for $4.50.

Answer 1

Answer

To graph the line of the proportional relationship you should plot the points (0, 0) and (18, 4.5), and then join the points with a line.

Explanation

Notice that is pretty obvious that 0 pencils cost 0 dollars, so our fist point will be (0, 0). Since x represent the number of pencils purchased and y the total cost, our second point will be (18, 4.5)

Now we can find the slope of our line using the point slope formula:

slope formula:

$m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}$

where  

$m$ is the slope of the line

$(x_{1},y_{1})$ are the coordinates of the first point on the line

$(x_{2},y_{2})$ are the coordinates of the second point

Since we already have our two points, we can replace the values in our formula:

$m=\frac{4.5-0}{18-0}$

$m=\frac{4.5}{18}$

$m=\frac{4.5-0}{18-0}$

$m=0.25$

Now that we have our slope, we can use the point slope formula to complete the equation of our line:

$y-y_{1}=m(x-x_{1})$

$y=0.25x$

Now, to graph the line that represents the proportional relationship, we will join the points (0, 0) and (18, 4.5) using our line.

Answer 2

(18,4.50) is the porportion relationship.