In performing lab work, in science courses and in science-related jobs, it is sometimes necessary to prepare a solution of a specific, desired concentration by diluting another solution of higher concentration. These "dilution problems" are a source of repeated difficulty for many students. You must master how to solve these kinds of problems.
First let's get some basic terminology straight. A solution has two components: the solvent and the solute. The solute is the substance that is dissolved in the solvent. Most often the solvent will be water, but there are many others possible, as you will see especially in chemistry courses (various alcohols, ethers, e.g.). And most often the solute will be some type of solid (salts, carbohydrates, amino acids, e.g.), but the solute may be a gas or even another liquid. For example, carbon dioxide (CO2) gas and oxygen (O2) gas are important solutes in your blood; and if you dissolved 5 mL of ethyl alcohol in 100 mL of water, the alcohol (a liquid) would be the solute in that solution.