Calculating image locations with thin lenses

[binhnguyent9]

Homework Statement

For each thin lens shown in the figure , calculate the location of the image of an object that is 18.5 {\rm cm} to the left of the lens. The lens material has a refractive index of 1.50, and the radii of curvature shown are only the magnitudes.

http://session.masteringphysics.com/problemAsset/1028455/6/1028455.jpg%20
s' (a)=?
s' (b)=?
s' (c)=?
s' (d)=?

Homework Equations

no1/f= (n-1) (1/R1-1/R2)

The Attempt at a Solution

none

 

[rl.bhat]

Using the relevant equation find the focal length of each lens.
Then using the formula
1/f = 1/do + 1/di find the position of the iamge.

 

[binhnguyent9]

i did use it, but for no reason when i put back to the answer, they said it is incorrect

 

[rl.bhat]

Show your calcualtions. With out that I can't see where your making mistakes.