${\bf A} = -17 \sin 70^\circ{\bf i} - 17 \cos 70^\circ{\bf j}$

${\bf A} = -15.97{\bf i} - 5.81{\bf j} \, \text{ m/sec}$

${\bf B} = 44 \cos 50^\circ{\bf i} - 44 \sin 50^\circ{\bf j}$

${\bf B} = 28.28{\bf i} - 33.70{\bf j} \, \text{ m/sec}$

${\bf R} = {\bf A} + {\bf B}$

${\bf R} = (-15.97 + 28.28){\bf i} + (-5.81 - 33.70){\bf j}$

${\bf R} = 12.31{\bf i} - 39.51{\bf j} \, \text{ m/sec}$

$R = \sqrt{{R_x}^2 + {R_y}^2} = \sqrt{12.31^2 + (-39.51)^2}$

$R = 41.39 \, \text{ m/sec}$ (*okay!*)

$\tan \theta_x = \dfrac{R_y}{R_x} = \dfrac{-39.52}{12.31}$

$\theta_x = -72.70^\circ$

$\theta_x = 72.70^\circ$ downward to the right (*ok!*)