Ratio and Proportion:

One of the most significant applications of fractional equations is ratio & proportion.  A ratio is a comparison of two such as quantities by division.  It is written through separating the quantities by a colon or by writing them as a fraction.  For write a ratio, the two quantities compared must be of the similar type.  For instance, the ratio of $8 to $12 is written as $8:$12 or $8/$12. Two except quantities cannot be compared by a ratio.  For instance, 1 inch and 30 minutes cannot form a ratio.  Therefore, two different units could be compared by a ratio if they measure the similar kind of quantity.   For instance, 1 minute and 30 seconds can form a ratio, that's why they must first be converted to the similar units.   Since 1 minute equals 60 seconds and the ratio of 1 minute to 30 seconds is written 60 seconds: 30 seconds, or   60 seconds/30 seconds, which equals 2:1 or 2.