An illuminated slide is held 44 cm from a screen. How far from the slide must a lens of focal length 11 cm be placed (between the slide and the screen) to form an image of the slide's picture on the screen? (Answer: 22 cm)

Question

anonymous · Answer

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where, of course, u is the object distance and v is the image distance.
Are you familiar with the formula $\frac{1}{u}+\frac{1}{v}=\frac{1}{f}$
Note that: 
The focal length is positive. 
u+v =44
Do you require further assistance?