I think it’s $34 but i’m not sure
At 4 seconds because 4 is the maximum point in the parabola
That would be f(x) = 4|x|. Reason is, the bigger the number that's multiplied by |x|, the narrower the graph will be. The opposite is true for the smaller the number, & so f(x) = .5|x| will be wider.
Hope this helps!