Answer
$F_{B}=1740N$
Work Step by Step
İf the system is in equilibrium, then the total torque is zero.
Lets write equation for total torque on point A and solve:
$\Sigma _{t=mg}\times L-F_{B}\times d=0\Rightarrow F_{B}=\dfrac {mg\times L}{d}=\dfrac {580N\times 4.5m}{1.5m}=1740N$
