21-a-or-an

public String aOrAn(String word) {
    //code here
    /* sol 1
    String vowels = 'aeiou'; 
    if(vowels.contains(word.substring(0,1) )) {
        return 'an '+word;
    }
    return 'a '+word; */

    // sol 2
    String vowels = 'aeiou';
    if(vowels.contains(word.substring(0,1)))
    {
        word = 'an ' + word;
    }else {
        word = 'a ' + word;
    }
    return word;
}