Mortgage interest income tax deduction on an investment property that has a 1st 2nd 3rd Mortgage

Selling price of the investment property is $1,500,000.00 and the buyer (your client) needed to get a 1st 2nd and 3rd mortgage

All your client remembers is that the 3rd mortgage rate is 12%

Two questions: What is the down-payment required and how much is the total interest amount to be claimed on the tax return?