alright, so I'm reviewing for a test I have on monday, and I was given a study guide which we must answer in order to get ready for the test. Now I just breeze through this stuff like its nothing, but I've found on discrepency. I even looked up the question online and i got 2 completely different answers, so, maybe someone here can guide me in the right direction, here it is.(adsbygoogle = window.adsbygoogle || []).push({});

A thermodynamic system undergoes a process in which its internal energy decreases by 500 J. If at the same time, 220 J of work is done on the system, find the heat transferred to or from the system.

its a simple dU = Q + W , but one place i found it ='s -720 [-500J - 220J] and the other I found it equaled -280 [-500J + 220J]. Any help is appreciated

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# Thermodynamics and internal energy stuck

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