if both the president and the vice president die who assumes power?

http://usgovinfo.about.com/library/weekly/aa010298.htm

If both the President and the Vice President of the United States were to die or be unable to fulfill their duties, the next in line to assume power would be the Speaker of the House of Representatives.

To find this information, you can refer to the United States Constitution, specifically the 25th Amendment. This amendment outlines the order of presidential succession in the event that the President is unable to fulfill their duties, whether due to death, resignation, removal from office, or temporary incapacity.

The 25th Amendment states that if the President is unable to discharge the powers and duties of the office, the Vice President becomes the Acting President. However, if both the President and the Vice President are unable to serve, the next in line is the Speaker of the House of Representatives.

It is important to note that this line of succession continues further, with the President pro tempore of the Senate and various cabinet members being next in line. The full order of succession is outlined in the Presidential Succession Act of 1947.