Answer:
$14.04
Explanation:
Let
x = yards of material
y = cost
The is a linear relationship between y and x that can be represented through the following equation.
y = m.x
where,
m is the slope, representing the cost per yard
If we have any 2 points (x₁, y₁) and (x₂, y₂), we can calculate m using the following expression.
m = y₂ - y₁ / x₂ - x₁
Let's use the first 2 points.
m = ($28.08 - $23.40)/ 6 yard - 5 yard = $4.68/yard
The final equation is
y = $4.68/yard . x
If Marnie wants to buy 3 yards (x = 3 yard),
y = $4.68/yard . 3 yard = $14.04