Question

Pls ans it question no 7 pls

Answer 1

m=3    f=r/2=18 cm (negative because it is a concave mirror 
using magnification formula:
m=-v/u
v=-3u
using mirror formula :
1/f=1/v+1/u
1/-18=1/-3u+1/u
1/-18=-1+3/3u
-1/18+2/3u
3u=-36
u=12 cm