Answer
$M_O=3070lb*ft\circlearrowleft$
Work Step by Step
We will sum the torques about point O
$M_O=(+ \circlearrowleft) \sum \tau_O$
$M_O=F*(4ft+\cos(45^{\circ})*3ft -1ft)$
$M_O=600lb*(4ft+\cos(45^{\circ})*3ft -1ft)$
$M_O=3070lb*ft$
$M_O=3070lb*ft\circlearrowleft$
