Answer
-21 kJ
Work Step by Step
∆E = q+w where q is the heat and w is the work.
As heat is released q is negative and is equal to -125 kJ. Here, work is done on the system. So it is positive and the value of w is equal to 104 kJ.
Then, ∆E = -125kJ + 104 kJ = -21 kJ
