Asystem absorbs 52 joules of heat and does work using 25 joules of energy. what is the change in the internal energy of the system?

B. 27 joules is correct

The change in internal energy is . Where is change in internal energy. is heat added to the system (absorbed by the system). work done on the system. is taken as positive if work is done on the system and negative if work is done by the system. Here and , hence change in internal energy is

Change in internal energy of the system is 27 J. Internal energy increases.