https://foxoyo.com/mcq/22596/study-the-following-number-series-to-answer-these-questions2-6-7-5-4-3-7-4-8-9-3-2-5-4-7-9-8-6-8-7-1-2-5-3-7-6-8-9-3-6how-many-7s-are-there-in-the-series-which-are-immediately-preceded-by-an-even-number-and-immediately-followed-by-an-odd-number