A ratio is simply a relationship between two numbers or a comparison between two different objects. The order of ratio is the key and it must be respected and held to at all times. Whichever object comes first in the list of consideration in comparison, that is the number that comes first when there are two being considered. Ratios are used to compare one thing to another. They are useful when it comes to the solving problems of proportions.
Separate the two numbers being compared with a colon. If you wanted to compare the numbers 5 and 7, you would write 5:7.
Write the ratio comparison as a fraction, also. Using the 5 to 7 comparison, you can also write it as, 5/7, and can also say, the ratio is five to seven.
Write the ratios the same way when comparing items within a list of three or more items. For example: Sally has three bottles, one apple, four cards and nine balls. To find the ratio of cards to balls, you will write the numerator in the fraction as the first quantity and the denominator as the second quantity, according to the guidelines at MathLeague.com. The fraction in this example would be 4/9. This ratio can be also written as 4:9 or 4 to 9.
If your question was the following for this example: "What is the ratio of bottles to the total number of items?"
There are three bottles, and 3 + 1 + 4 + 9 = 17 items in total.
The ratio answer is 3/17, or 3 to 17, or 3:17.
Order matters when it comes to ratios. 6/1 is not the same as 1/6.