You'll need to multiply the function out to get it in the form y = ax^2 + bx + c, in this case it would be y = 4x^2 + 16x + 20.
We can immediately see that y = 20 would be the y value for the pivot point for the equation, and since the equation is positive it woukd have a concave shape. Thus it woulc be a minimum of 20, since there are no points lower than that on the y-axis.
Plotting functions like this on desmos helps you get a better understanding of how they work. I recommend you try! ;)
1 ton = 2000 pounds
2000*16=32000ounces
32000/5 = 6400 parts
Original cost -total cost to get amount of tax.
