The table below shows the size of the graduating classes for to high schools.

Answer:
2017
Step-by-step explanation:
Adams high school Butler High school
628, 625, 622, 619, 616, 613, 436, 449, 462, 475, 488, 501
common difference = 625 - 628 = -3 common difference = 449-436 = 13
we can continue series like this
613 - 3 = 610 [2011] 501 + 13 = 514
610 - 3 = 607 [2012] 514 + 13 = 527
607 - 3 = 604 [2013] 527 + 13 = 540
604 - 3 = 601 [2014] 540 + 13 = 553
601 - 3 = 598 [2015] 553 + 13 = 566
598 - 3 = 595 [2016] 566 + 13 = 579
595 - 3 = 592 [2017] 579 + 13 = 592
I assume when they will become equal
so it is 2017