Interview question

Marketing adds up the bookings that each channel's own platform report claims: paid search 45,000, social 30,000, email 25,000, affiliate 20,000 (hypothetical monthly figures; each platform credits itself when it saw a click or view of its own ad within its window). Total bookings in the data warehouse are 80,000. The CFO asks why claimed bookings are 150% of actual bookings and whether to cut paid search. How do you resolve this and what measurement would you set up?