By now, you will have plenty of practice of simplifying fractions and ratios to their simplest form by finding the HCF.
One of the things that you will have been told is that you cannot have decimals in the simplified versions.
There is however one exception to this rule.
You could be asked to write a ratio in the form 1:n or m:1. All this means is that either the first number must be 1 (1:n) or the second must be 1 (1:m).
This frequently means you have a decimal for the other number. In this situation, that is fine.
Example 1: Write 5:8 in the form 1:n.
As we are looking for 1:n, this means the first number must be 1 and the second can be a decimal.
To make the first number 1, we have to divide by 5 (5 ÷ 5 = 1)
So we divide both sides by 5
1 : 1.6
Example 2: Write 25:10 in the form m:1.
As we are looking for m:1, this means the second number must be 1 and the first can be a decimal.
To make the second number 1, we have to divide by 10 (10 ÷ 10 = 1)
So we divide both sides by 10
2.5 : 1