In the book of Melachim Alef 22:42 it says:
Jehoshaphat was thirty and five years old when he began to reign; and he reigned twenty and five years in Jerusalem.
Seder Olam (see here) agrees with that:
בשנת שלשים ושמנה שנה לאסא מלך יהודה (מלך) [וימלך] אחאב בן עמרי על ישראל [בשמרון] עשרים ושתים שנה (שם טז כט), בשנת ארבע לאחאב מלך יהושפט, בן ל"ה שנה היה במלכו, כ"ה שנה מלך בירושלם
But looking at Sefer haKabbalah it seems that it does have some 'inconsistences' (perhaps, due to typo?). Compare for instance, here it says 28 years and also here, but here it says 21 and here 95. Am I missing something? Which one is correct? And if is one of these, which differs from SO and the posuk above, what source and reasoning supports it?