Yoram Insists on Consuming 4 Times as Much of Y

Yoram insists on consuming 4 times as much of 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 3 times the price of y. Yoram has an endowment of 20 x's and 45 y's which he can trade at the going prices. He has no other source of income. What is Yoram's gross demand for x?

A) 105
B) 65
C) 15
D) 12
E) We can't determine the answer without knowing the price of x.