Read this article and answer this question In addition to these councils there have been a number of other significant councils meant to further define the Orthodox position. They are the Synods of Constantinople, in 1484, 1583, 1755, 1819, and 1872, the Synod of Jassy in 1642, and the Pan-Orthodox Synod of Jerusalem in 1672. Another council convened in June 2016 to discuss many modern phenomena including Modernism, other Christian confessions, Orthodoxy's relation with other religions and fasting disciplines.
How many years apart are the Synod of Jassy and the Pan-Orthodox Synod of Jerusalem?
30