see the picture attached to better understand the problem
we know that
C is the center of the circle
CR=CS-----> is the radius of the circle
CR and AB are perpendicular
the triangle SCR is a isosceles triangle
angle SCR is equal to 80°------> is a central angle
angle CSR and angle CRS are equal to 50°----> because 80+50+50=180
therefore
m∠SRA=90°-m∠CRS------> m∠SRA=90°-50°=40°
the answer is
m∠SRA=40°
