Group the report by staff and place staff, Art, Sport, Music as text fields in Group header.
now in details section place data as
Staff, formula 1 (If Category='Art' then Amount), formula 2 (If Category='Sport' then Amount), formula 3 (If Category='Music' then Amount)
If Staff has only one value then its ok else place Staff in Group footer and take sum of all values in group footer (Don't remove Formula 1,2,3 from details)