Find magnitude of the radius of curvature of the mirror?

A convex spherical mirror forms a virtual image 0.52 times the size of the object. The distance between object and image is 14.4 cm. How do you find magnitude of the radius of curvature of the mirror????

We use the lens eqn 1/s + 1/s’ = 2/R where s is the object distance and s’ is the image distance

also the magnification m = s’/s so s’ =m*s = 0.52*s

For a virtual image s’ is negative

Since the distance between s & s’ = 14.4cm we have 0.52s + s = 14.4=> s = 14.4/1.52 = 9.47cm

and s’ = -0.52*9.47 = -4.93cm

So 2/R = 1/9.47 + 1/(-4.93) = -0.0974

So the magnitude of R = 2/0.0974 = 20.5cm