CREATE TABLE table_15202 ("Year" FLOAT, "Entrant" TEXT, "Chassis" TEXT, "Engine" TEXT, "Points" FLOAT)

What year has an ERA engine and an ERA A-type chassis?
SELECT "Year" FROM table_15202 WHERE "Engine" = 'era' AND "Chassis" = 'era a-type'
SELECT "Year" FROM "table_15202" WHERE "Chassis" = 'era a-type' AND "Engine" = 'era'