The function f(t) = -0.15t² + 0.53t + 30.4 models the U.S. population in millions, ages 65 and older, where t represents years after 1990. The function g(t) = 0.56t² + 12.6t + 105.6 models the total yearly cost of Medicare in billions of dollars, where t represents years after 1990. Find (g/f)(12).