When a red blood cell is placed into a saltwater solution, it experiences osmosis, which is the movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. In this case, since the salt concentration in the solution is higher than that inside the red blood cell, the solution is considered hypertonic compared to the cell.
As a result, water will exit the red blood cell to balance the solute concentrations, causing the cell to shrink or crenate. This change occurs because the higher salt concentration outside the cell draws water out, leading to dehydration of the cell.
In summary, the salt concentration in the solution is higher (hypertonic) compared to the inside of the red blood cell.