What is the formula for determining image distance in a convex mirror?

[Knfoster]

Homework Statement

An object is placed 32.7 cm from the reflecting surface of a convex mirror having a focal length of -10.8 cm. Determine the image distance.

Homework Equations

IDK

The Attempt at a Solution

Could someone please tell me what equation I should use? Thanks!

 

[tuomas22]

Object-image relation:

1/s + 1/s' = 1/f

where

s = object distance
s' = image distance
f = focal length

 

[Knfoster]

Thank you!