The resultant force on the system is equivalent to the difference in the weights of the chandelier and Robin Hood.
F(net) = 240g - 85g
F(net) = 155g
Robin Hood's Acceleration:
F = ma
155g = 85a
a = 17.89 m/s²
Tension = mg + ma
Tension = 85(g + a)
Tension = 2400 N