Thread: Pareto Optimal Allocation

An economy consist of 2 people.
Person 1 has endowment of (3,12)
Person 2 has endowment of (6,6)
They have the same Utility function: U(x,y)=XY
At every Pareto Optimal Allocation,
(is a multiple choice and answer is : "Person 1 consumes 9 good x for every 18 good y that he/she consumes")

I couldnt seem to get close to the answer.

At Pareto Optimal, their MRS(1)=MRS(2)=P(1)/P(2){"Price 1 and 2"}, and then i dont know how to continue to get the answer

Any help will be appreciated
Edit: this is question is based on Competitive/Walrasian Equalibirum

Thanks in advance