In this question, we are given the density of oil, water and the block. We are given that the block is floating, and thus we need to find what fraction of the block's volume lies in the oil. I have a very simple question; which equation is correct:
Weight of block + weight of displaced oil = weight of displaced water (implying that oil exerts buoyant force downwards)
weight of block = weight of displaced oil + weight of displaced water (implying that buoyant force due to oil is upwards, which doesn't make sense to me whatsoever).
This question involves the exact same doubt, but clearly there was some confusion between the writer of the accepted answer and the asker (see comments). In the end however, the answerer said that oil exerts force downwards. Is this buoyant force? (if it was I could say that the downwards buoyant force due to oil is equal to weight of volume of oil displaced, which would be equal to the fraction of volume of block in the oil) Or is it the force due to pressure of the oil above the block (in which case I could calculate it using the formula $\rho_0 + \rho gh$. If I do use this formula would I need to find the net force due to difference of pressures at the bottom and top? How exactly do I do that when the density changes at some unknown depth? Are they equivalent?
Reading through this thread honestly just confused me even more, some people involved said the force due to oil is downwards, but I'm not sure if it's right to call that the buoyant force. I also read somewhere that I should just find the total amount of oil and water displaced (fraction of block's volume in each liquid times the respective density times $g$) and their sum would be equal to the weight of the block. This would imply that despite the oil being entirely above the block (none below it) it somehow contributes to the buoyant force.
Clearly, I have some major confusion about what causes buoyant force, and the difference between buoyancy and pressure. I would really appreciate it if someone could systematically answer my questions and clear my confusion :)