During sales hour in a supermarket, Cynthia measures her urgency from buying x bags of candies and y bars of chocolate using the following function: f(x, y) = xy. If Cynthia has USD 5.00 to spend and each bag of candies and each bar of chocolate cost USD 1.50 and USD 1.00, resp., how many bags of candies and bars of chocolate should she purchase to maximize her urgency? Use Lagrange Optimization to solve this problem.