A ratio is the amount of one object (or one type of object) compared to another one. In math, ratios are used to compare the values of different objects.
Ratios are written in three different ways. The first is by a colon, written as "2:1." The second way a ratio is written is to utilize the word "to" instead of using a colon, as in the phrase "2 to 1." Ratios can also be written as a fraction with a slash, as in "2/1."
A rule of ratios is to divide or multiply numbers of the same value; the units must be the same so they can be comparable.