When the letter /X/ is in a word it is USUALLY pronounced in one of two ways:
- If the /X/ is between a vowel and consonant sound then it is usually pronounced as /KS/
- If the /X/ is between two vowel sounds then it is usually pronounced as /GZ/
Of course, there is always an exception to every pronunciation rule in English. If the letter X is at the beginning of a word, then it is sometimes pronounced Z.
X pronounced KS: excel, except, extermination, sixth
X pronounced as GZ: exact, exam, exoneration
X pronounced as Z: xylophone