An extended object is placed at point \( O \), \( 10 \, \text{cm} \) in front of a convex lens \( L_{1} \) and a concave lens \( L_{2} \) is placed \( 10 \, \text{cm} \) behind it, as shown in the figure. The radii of curvature of all the curved surfaces in both the lenses are \( 20 \, \text{cm} \). The refractive index of both the lenses is \( 1.5 \). The total magnification of this lens system is :
