user: Question: What is the mintage (bu) with the artist Royal Canadian Mint Staff and has an issue price (proof) of $54.95?
Columns: ['Year', 'Theme', 'Artist', 'Mintage (Proof)', 'Issue Price (Proof)', 'Mintage (BU)[ clarification needed ]', 'Issue Price (BU)[ clarification needed ]']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [2000.0, 'Voyage of Discovery', 'D.F. Warkentin', '121,575', '$29.95', '62,975', '$19.95']
SQL:

assistant: SELECT "Mintage (BU)[ clarification needed ]" FROM "Table" WHERE "Artist" = 'Royal Canadian Mint Staff' AND "Issue Price (Proof)" = '$54.95';