Mortgage loan

I did cash-out refinance on our main home to buy a rental property.  We paid off the loan for our main home and used the rest of money to buy a rental property.  How would I calculate our interest amount to deduct for our property expense?   The paid off was about $150,000 and we used about $500,000 (The refinance loan amount is $650,000) to buy a property and also took $50,000 out of our saving.