19 and 13/25 is your answer.
I think so I am not too sure
I won't do this for you, but I can give you a hint. Replace your f variable with -2, -1, 0, 1, and 2. Then take said f variable and put it in your y boxes. Then just get a calculator and do the work on there. It should be pretty easy.
Divide the current year by the previous year then multiply it by 100.
We use different models for different types of variation. For example, linear variation is associated with the formula y=ax, or the more familiar y=mx+b (the equation of a straight line). Cubic variation: y=a*x^3. In the present case we're discussing quadratic variation; perhaps that will ring a bell with you, reminding you that y=ax^2+bx+c is the general quadratic function.
Now in y our math problem, we're told that this is a case of quadratic variation. Use the model y=a*x^2. For example, we know that if x=2, y =32. Mind substituting those two values into y=a*x^2 and solving for y? Then you could re-write y=a*x^2 substituting this value for a. Then check thisd value by substituting x=3, y=72, and see whether the resulting equation is true or not. If it is, your a value is correct. But overall I got 16!