Solving for Resultant Angel

i got a to be 6919.255 N by solving for the resultant force. when i tried to solve for the resultant angel, i used O=tan^-1 (Fy/Fx) .... (-6272.03/-2921.93) and came up with 24.979..then since it have to be in the clockwise direction, i subtracted 180..and got -155. this was incorrect.

In earlier days, horses pulled barges down canals in the manner shown in Fig. 5-47. Suppose the horse pulls on the rope with a force of 7800 N at an angle of θ = 22° to the direction of motion of the barge, which is headed straight along the positive direction of an *x* axis. The mass of the barge is 9600 kg, and the magnitude of its acceleration is 0.10 m/s2. What are (a) the magnitude and (b) the direction of the force on the barge from the water? (Measure the direction *clockwise* from the direction of motion, and give your angle to the nearest degree.)