How to solve this physics problem (buoyancy)

Please give the equation to solve this:

A block has a density of 2.70 g/cm^3 and mass of 775 g. It is submerged in a fluid with a density of .650 g/cm^3. How much of the fluid does the block displace?

Volume of the block = (775/2.7) = 287.04 cc. That is the volume of the liquid displaced.
The displaced mass = (287.04 x .65) = 186.58g.

Not sure which you wanted, mass or volume.

if the quoted density of the fluid is correct, the block is denser than the fluid, therefore it will sink and will displace an amount of fluid equal to the volume of the block

the volume of the block = mass/density = 775g/2.7g/cm^3 = 287cm^3

this is the volume of fluid displaced; the mass of this much fluid is

mass = density x volume = 0.65g/cm^3 x 287cm^3 = 187g