I believe that the answer is a
The object should be placed 20/cm from the lens so as to form its real image on the screen
<h3>Mirror equation</h3>
The mirror equation is given according to the expression below;
1/f = 1/u + 1/v
where
f is the focal length
u is the object distance
v is the image distance
Given the following parameters
f = 5cm
v = 20cm
Required
object distance u
Substitute
1/5 = 1/u +1/20
1/u = 1/5-1/20
1/u = 3/20
u = 20/3 cm
Hence the object should be placed 20/cm from the lens so as to form its real image on the screen
Learn more on mirror equation here; brainly.com/question/27924393
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12 +4m = 24
4m = 12
m = 12/4
m = 3 so choice C. is right sure


Simplification

Subtract sides 2

Simplification

Subtract sides -12x

Simplification

Divided sides by -6


It is must be in the box buddy.
And we're done...♥️♥️♥️♥️♥️