The equation that relates the work, heat and internal energy is given below.
ΔU = Q - W
where ΔU is the change in internal energy, Q is the heat (positive when added to the system and negative when removed from the system), W is work (- when done by the system and + when done on the system)
Substituting the known values,
ΔU = (5.00 x 10^2 kJ) x (1 kcal/4.18 kJ) - 325 kcal
ΔU = -205.38 kcal
