We use the term proportion quite often in our daily lives. In English, proportion means a part or portion, to the whole. In mathematics, two varying quantities are said to be in a relation of proportionality, if they are multiplicatively connected to a constant. That is when either their ratio or their product yields a constant. The value of this constant is called the coefficient of proportionality or proportionality constant. Proportion is an expression which states that the two given ratios are equal. In very basic terms, the proportion determines the equality of two ratios. The term direct proportion means that two (or more) quantities increase or decrease in the same ratio. For example, in the purple paint mixture, the ratio of blue to red of 4:3. It does not necessarily mean we every mixture would have 4 red and 3 blue cans.