A body weights 200 gm in air 180 gm in a liquid and 175 gm in water. The density of the material of the body is 

m_air = 200 mg
Also, it weighs 175g in water (water has a density of 1g/cc).

Then,

$$\begin{gathered} 175g=200g-(V\times 1\times g) \\ \Rightarrow V=25 cc \end{gathered}$$

density of material of body,

$\rho =\frac{m_{air}}{V_{body}}=\frac{200}{25}=8 g/cc=8000 kg/m^3$