The ratio is the ratio of the number of the previous item divided by two numbers, and it is not necessary to ask for fractions, fractions or decimals. For example, you will understand: 4: 5 = 4/5 = 0.2 = 1/5.
The simplified ratio is a ratio of 4: 2, which is 2: 1 after simplification.
Comparison is to find a comparison. For example, the ratio of 3 to 1 is 3 (the former): 1 (the latter).