Pablo insists on consuming 4 times as much y as he consumes of x (so he always has y = 4x). He will consume these goods in no other ratio. The price of x is 5 times the price of y. Pablo has an endowment of 15 x0s and 60 y0s which he can trade at the going prices. He has no other source of income. What is Pablo's gross demand for x?