Suppose you have some utility function that defines the consumption of goods x and y$,$ with the following marginal utilities, M U subscript x equals space y and M U subscript y space equals space x$.$

The prices of these goods are given as P subscript x space equals space $3$ space and space P subscript y space equals space $4.$

What is the optimal consumption for good y$,$ given income I space equals space $1$ comma $200.$