physic last help?

Question

a concave mirror has a radius of curvature of 0.50cm.
where an object in front of the mirror must be placed in such a way that its image forms to 0,15 m behind the mirror

to 0.38m
b 0,19 m
c 0,093 m
d 0,77 m
and 0.57

Answer 1

See ref

1/d + 1/b =1/f
f - focal distance
d - distance of the object before the mirror
b- distance of image appearing behind the mirror

f=0.5 R = 0.5 (0.50)= 0.25 cm
b= 0.15 m

then
d=1/(1/f - 1/b)