John has two daughters, S and X.
S = 18 years old
X = 9 years old
Now, if I want to compare their ages, how do you say it naturally?
I have written these three sentences, do they sound good to native speakers?
S's age is twice as old as X's age
S's age is twice X's age
S's age is 2 times older than X's
After reading the comments and answers, I still don't understand why sentence 3 is not correct, Could you explain it please?