Answer:
Well for the onion peel, since its a plant cell...it shall gain water from the solution as it has a lower water potentail,and hence increase in size, becoming turgid and tight, with the cell wall exerting pressure to stop it from bursting.
For the RBC, its an animal cell, and shall also gain water, but since there is no cell wall to support it, it shall soon gain so much water that it shall burst becuase of the pressure, through lysis, and shall die.
Note, the plant cell does not die.