We can solve the problem by using the first law of thermodynamics:
\(\Delta U= Q-W\)
where
\(\Delta U\) is the variation of internal energy of the system
Q is the heat added to the system
W is the work done by the system
In this problem, the variation of internal energy of the system is
\(\Delta U=U_f-U_i=134 J-87 J=47 J\)
While the heat added to the system is
\(Q=500 J\)
therefore, the work done by the system is
\(W=Q-\Delta U=500 J-47 J=453 J\)
