Imagine there are two series of science-fictions:The Three-Body Problem(T) andGalactic Empires(G).Your utility function is U = TG, where T is the number of books you consume forThe Three-Body Problem, and G is the number of books you consume forGalactic Empires.If your budget is $200, the price of each book ofThe Three-Body Problem(T) is $50, and the price of each book ofGalactic Empires(G) is $100.

Now imagine the price ofGalactic Empires(G) decreases to $50.How many books ofGalactic Empires(G) do you consume now?