Two SetFloats interacting

a(0)
b(0)

a(t) = (b(t) - a(0))t + a(0)
b(t) = (a(t) - b(0))t + b(0)

a(t) = (((a(t) - b(0))t + b(0)) - a(0))t + a(0)

a(t) = t^2 (a(t) - b(0)) + t (b(0) - a(0)) + a(0)

a(t) = (a(t) - b(0))t^2 + (b(0) - a(0))t + a(0)
a(t) = a(t)t^2 - b(0)t^2 + (b(0) - a(0))t + a(0)

a(t) - a(t)t^2 = -b(0)t^2 + (b(0) - a(0))t + a(0)
a(t)(1 - t^2) = -b(0)t^2 + (b(0) - a(0))t + a(0)

a(t) = (-b(0)t^2 + b(0)t - a(0)t + a(0)) / (1 - t^2)

a(t) = (-b(0)t^2 + ((b(0) - a(0))t + a(0)) / (1-t)(1+t)

Per Wolfram Alpha for polynomial division

a(t) = (b(0)t + a(0))/(1+t)