CREATE TABLE table_24660 ("Year" FLOAT, "Starts" FLOAT, "Wins" FLOAT, "Top 5" FLOAT, "Top 10" FLOAT, "Poles" FLOAT, "Avg. Start" TEXT, "Avg. Finish" TEXT, "Winnings" TEXT, "Position" TEXT, "Team ( s ) " TEXT)

Name the avg start for avg finish of 18.3
SELECT "Avg. Start" FROM table_24660 WHERE "Avg. Finish" = '18.3'
SELECT "Avg. Start" FROM "table_24660" WHERE "Avg. Finish" = '18.3'