For point A. You know that 5 pounds cost $17.50 and 30 pounds cost $105. So you can do the following graph
Now, for point b you can use the following formula to find the equation of the line that you already graphed
[tex]\begin{gathered} m=\frac{y_2-y_1}{x_2-x_1_{}} \\ m=\frac{105-17.5}{30-5} \\ m=\frac{87.5}{25} \\ m=3.5 \end{gathered}[/tex]
That means that the slope of the line is 3.5, now with this data you can use the following formula
[tex]\begin{gathered} y-y_1=m(x-_{}x_1) \\ y-17.5=3.5(x-5) \\ y-17.5=3.5x-17.5 \\ y-17.5+17.5=3.5x-17.5+17.5 \\ y=3.5x \end{gathered}[/tex]
Therefore, the equation of the line that describes what Ferroza's pet ferret spends on food is
[tex]y=3.5x[/tex]
Now to find the value of y at the point (1, y), take x=1 into the equation of the line
[tex]\begin{gathered} y=3.5x \\ y=3.5(1) \\ y=3.5 \\ \text{Then,} \\ (1,y)\rightarrow(1,3.5) \end{gathered}[/tex]
Finally, like the equation of the line that describes what Ferroza's pet ferret spends on food, then Ferroza wants to know what the value of y is, to know how much a pound of his pet's food is worth.
