In a salt solution, the water potential is lower than that in the cell. In this case, water molecules will flow from a region of higher water potential to a region of lower water potential by osmosis. Which where water molecules is now flowing out of the cell to the salt solution. Because the cell lose so much water that it now shrinks. Osmosis is where water molecules move down the water potential gradient through a semi permeable membrane, which is the cell membrane in this case.
You simply add the volumes :) If this was a case that involved titration, you would use the formula M1V1 = M2V2. I do not know if that is what you were referring to but based on the information you gave, you simply add the two volumes.
What would be the value of g on the surface of the earth if its mass was twice and its radius half of what it is now ? g2=8g1 Thus , the value of g on the surface of the earth would be eight times the present value.