Answer: A proportion is simply a statement that two ratios are equal.
Example: 2:6 = 1:3
To get that you do this: 2:6 ÷ 2:2 = 1:3
-----------------------------------------------------------
Example 2: 5:10 = 1:2
To get that you do this: 5:10 ÷ 2:2 = 1:2