CREATE TABLE table_75151 ("Player" TEXT, "Position" TEXT, "Starter" TEXT, "Touchdowns" FLOAT, "Extra points" FLOAT, "Field goals" FLOAT, "Points" FLOAT)

What is the lowest number of touchdowns for left halfback WIllie Heston who has more than 15 points?
SELECT MIN("Touchdowns") FROM table_75151 WHERE "Position" = 'left halfback' AND "Player" = 'willie heston' AND "Points" > '15'
SELECT MIN("Touchdowns") FROM "table_75151" WHERE "Player" = 'willie heston' AND "Points" > '15' AND "Position" = 'left halfback'