You have to use Dalton's law of partial pressure for this question. Dalton's law of partial pressure basically states that the total pressure of the system is all of the partial pressures of the components added together. Therefore to answer the question you just need to add all the patial pressures together meaning that the total pressure would be 700+500+500=1700.
The answer would be 1700 torr.
I hope this helps. Let me know if anything is unclear or if you have any further questions.
