an object 2.6 cm high is 24cm from concave mirror whose radius of curvature is 16cm. Determine the location of its image.

Question

the answer is 12cm in front of mirror.

I want to know what to get this. What steps and which formulas are used?
please help

Answer 1

f=r/2
so f=16/2=8

1/di + 1/do = 1/f
1/di + 1/24 = 1/8
1/di= 1/8 - 1/24
1/di= 1/12
di = 12
magnification = - di/do
M = - 12/24 = -.5