Two different combinations of solute and solvent can make solutions with the same concentration if they have the same number of moles of solute per liter of solution. For example, a 1 M solution of NaCl and a 1 M solution of KCl will both contain 1 mole of solute per liter of solution, even though they are made up of different solutes and solvents.

To calculate the concentration of a solution, you need to know the number of moles of solute and the volume of the solution in liters. The formula for concentration is:

```

concentration = moles of solute / liters of solution

```

For example, if you dissolve 1 mole of NaCl in 1 liter of water, the concentration of the solution will be 1 M. If you dissolve 1 mole of KCl in 1 liter of water, the concentration of the solution will also be 1 M.

Even though the two solutions have the same concentration, they will not necessarily have the same properties. For example, a 1 M solution of NaCl will be more conductive than a 1 M solution of KCl, because NaCl is a stronger electrolyte.