$P_x = 500(\frac{1}{\sqrt{2}}) = 353.55 \, \text{ lb}$ to the right

$P_y = 500(\frac{1}{\sqrt{2}}) = 353.55 \, \text{ lb}$ upward

$Q_x = 361(\frac{3}{\sqrt{13}}) = 300.37 \, \text{ lb}$ to the right

$Q_y = 361(\frac{2}{\sqrt{13}}) = 200.25 \, \text{ lb}$ downward

$M_O = 5Q_y = 5(200.25)$

$M_O = 1001.25 \, \text{ lb}\cdot\text{in.}$ clockwise

$R_x = P_x + Q_x = 353.55 + 300.37$

$R_x = 653.92 \, \text{ lb}$ to the right

$R_y = P_y - Q_y = 353.55 - 200.25$

$R_y = 153.3 \, \text{ lb}$ upward

x-intercept of the resultant

$aR_y = M_O$

$a(153.3) = 1001.25$

$a = 6.53 \, \text{ in.}$ to the left of point O *answer*

y-intercept of the resultant

$bR_x = M_O$

$b(653.92) = 1001.25$

$b = 1.53 \, \text{ in.}$ above point O *answer*