Concentration of a Solution is the amount of solute present in a solution
Different Methods to Calculate Concentration

Mass by Mass %
 Concentration of Solution = (Mass of Solute / Mass of Solution) × 100

Mass by Volume %
 Concentration of Solution = (Mass of Solute / Volume of Solution) × 100

Volume by Volume %
 Concentration of Solution = (Volume of Solute / Volume of Solution) × 100
Let's do Examples of each
Mass by Mass %
Suppose 100 grams of salt is mixed in 400 grams of water
It forms 500 grams of solution
Concentration of Solution = Mass of Solute / Mass of Solution × 100
= (100 / 500) × 100
= 20%
Mass by Volume %
Calculate the concentration in terms of mass by volume percentage of the solution containing, 2.5g potassium chloride in 50ml of potassium chloride (KCl) solution?
Mass of Solute (Potassium Chloride) = 2.5 g
Volume of Solution = 50 mL
Concentration of Solution = Mass of Solute / Volume of Solution × 100
= (2.5 / 50) × 100
= 5%
Volume by Volume %
If 2 mL of acetone is present in 45 mL of its aqueous solution, calculate the concentration of this solution
Volume of Solute (Acetone) = 2 mL
Volume of Solution = 45 mL
Concentration of Solution = Volume of Solute / Volume of Solution × 100
= (2 / 45) × 100
= 4.44 %