Use formula to work out the image distance for each situation below. Assume that you have a 5.0cm concave lens (f=5.0cm), and that the object height is 8.0cm.

1) When Objectdistance=20cm

2) When Objectdistance=10cm

3) When Objectdistance=15cm

4) When Objectdistance=4.0cm

Working would be appreciated and im aware it isnt too difficult. Thx :)