t: 0
f0: floor(t / 5) + 1
h: t - ((f0 - 1) * 5) + 1
f(x) = (f0 * ℯ^((-(x / h))))
A = Intersect(f, yAxis, (0, 1))
g = Tangent(A, f)
k = Intersect(g, xAxis)