SELECT AVG("Track") FROM table_7127 WHERE "Writer(s)" = 'mac davis'
Which Track has a Writer(s) of mac davis?
CREATE TABLE table_7127 (
    "Track" real,
    "Recorded" text,
    "Catalogue" text,
    "Release date" text,
    "Chart peak" text,
    "Song title" text,
    "Writer(s)" text,
    "Time" text
)