Radius of curvature(r)=12cm

focal length(F) = r ÷ 2 → 12 ÷ 2 = 6cm

therefore F = 6cm

magnification(M) = v ÷ u
1.5 = v ÷ u

:v = 1.5u

Using mirror formula
1/f =1/v + 1/u

\(\frac{1}{6}\) =\(\frac{1}{1.5u}\) + \(\frac{1}{u}\)
\(\frac{1}{6}\) = \(\frac{1 + 1.5}{1.5u}\)
\(\frac{1}{6}\) = \(\frac{2.5}{1.5u}\)
1 * 1.5u = 2.5 * 6
u = \(\frac{15}{1.5}\) = 10
therefore object distance =10cm.