Explanation

(a) According to Cartesian sign convention
Object distance, $u = - 15\ cm$
Focal length, $f = - 10cm$
Using mirror formula $\frac{1}{u} + \frac{1}{v} = \frac{1}{f} \Rightarrow \frac{1}{( - 15)} + \frac{1}{v} = \frac{1}{( - 10)}$
$\frac{1}{v} = \frac{1}{( - 10)} - \frac{1}{( - 15)} + \frac{1}{( - 10)} + \frac{1}{(15)}\ $or$\ v = - 30cm$
This image is $30\ cm$ from the mirror on the same side of the object
Magnification, $m = - \frac{v}{u} = - \frac{( - 30\ cm)}{( - 15cm)} = - 2cm$
The image is magnified, real and inverted