$$ ∴ Σ F_x ( → +ve )= R_x $$

$ =22.5 \cos⁡ 4.51-30 \cos⁡ 30 \\ = -10.07 N \\ = 10.07 (←) \\ ∴ Σ F_y ( ↑+ve )= R_y=15+22.5 \sin 45-30 \sin 30 \\ =15.56 N (↑) \\ ∴ \text {Resultant force (R) } = \sqrt{R_x^2+R_y^2 }= \sqrt{(-10.0.7)^2+(15.56)^2 } \\ ∴R=18.53 N \\ θ= \tan^{-1} \Bigg(\dfrac {R_y}{R_x}\Bigg) = \tan^{-1} ⁡ \Bigg( \dfrac {15.56}{-10.07}\Bigg)=180-57.09=122.91°$