It is. The reason? I will explain
2:9 is equal to 4:18 because if you multiply both sides by 2, they are 4:18.
So as long as you multiply both sides evenly by the same number, they are equivalent as you see
So lets try the other way around and reduce.
Get 4:18 and divide both sides by 2
4÷2=2 and 18÷2=9 so it would be 2:9
Answer: So yes, based on what I showed you, they are equal.