1. The problem statement, all variables and given/known data The internal energy of a system increases by 200 J while 900 J of work are performed on it. What was the magnitude of the heat flow into or out of the system? Does the heat flow "out of" or "into" the system? 2. Relevant equations Don't really need. 3. The attempt at a solution I found the magnitued already, being 700 Joules, but I'm not entirely sure about the second question. I think it's "out of," but don't really know. How do I evaluate this aspect of the question?