A light ray is incident, at an incident angle $\theta$₁, on the system of tow plane mirrors M₁ and M₂ having an inclination angle 75$^\circ$ between them (as shown in figure). After reflecting from mirror M₁ it gets reflected back by the mirror M₂ with an angle of reflection 30$^\circ$. The total deviation of the ray will be _____________ degree.