CREATE TABLE table_203_610 (id NUMBER, "institution" CLOB, "location" CLOB, "nickname" CLOB, "founded" NUMBER, "historical affiliation" CLOB, "enrollment" NUMBER, "primary conference" CLOB)

what is the total enrollment when you add brown university and union college ?
SELECT SUM("enrollment") FROM table_203_610 WHERE "institution" IN ('brown university', 'union college')
SELECT SUM("enrollment") FROM "table_203_610" WHERE "institution" IN ('brown university', 'union college')