Answer
$W_e = -0.234\ kWh$
Work Step by Step
The energy balance for this system reduces to:
$Q_{lost}-W_e=\Delta H= mc_p\Delta T$
With $c_p=1.005\ kJ/kg.K, Q_{lost}=-60\ kJ$
we can solve for $W_e =-843.9\ kJ \times \frac{1\ kWh}{3600\ kJ} = -0.234\ kWh$
