physics
posted by Lines in the Sand122 .
A 2.6 cm thick bar of soap is floating on
a water surface so that 2.14 cm of the bar is underwater. Bath oil (of specific gravity 0.8)is poured into the water and floats on top of the water.
What is the depth of the oil layer when the top of the soap is just level with the upper surface of the oil?
Answer in units of cm.

The soap is floating in water, you can get its weight from the volume of water displaced.
Now in the second part, the volume displaced is two weights, the sum of which equals the original weight.
The top weight is the volume of oil displaced, the lower weight the the weight of water displaced. For computing purposes, assume the area of the bar is A. (thickness*A=volume). 
dsfd