[Khyati]

What will be the effect of pressure on the melting point to the equilibrium system of solid  liquid and on the boiling point to the equilibrium system of liquid  vapor ?

I think in above cases melting point and boiling point may increase or decrease depending upon the nature of solid and liquid respectively. I am not sure though 

[opti384]

For solid liquid, usually the melting point increases if the pressure increases, but of course there are exceptions like water. If you check phase diagram you figure out the effect of pressure. For liquid  gas, think about the vapor pressure and the definition of the boiling point.

[Borek]

Think in terms of LeChatelier's principle. There is a volume change during phase transition, if you increase the pressure system will try to get to lover volume.

[MrTeo]

In addition to what opti384 said you can always think at it from a slightly more "mathematical" point of view using Clapeyron's equation:

$$ \frac{dP}{dT}=\frac{\Delta H}{T \Delta V} /$$

Obviously in this case you only need to roughly evaluate the changes (∆) to see whether they're positive or negative...

[Khyati]

Thanks a lot