Refer to figure.
Note: Another version of this classic question, reported with a slight rewrite. This time there are 3 infants on their own seat and also 525 kg of additional bulk cargo to include.

Traffic Load is the total mass of passengers, baggage and cargo including any non-revenue load.

Points to note from this question:

• Flight crew members are not part of the Traffic Load so ignore their details.
• According to the annex, aircraft with more than 30 seats may use an "all adult" standard mass of 84 kg.
• Children will be 35 kg standard mass.
• Infants (ages less than 2 years) using the same seat as their parents, count as 0 kg towards the load. Infants on their own seat count as a child (35 kg)
• From the annex, European flights use 13 kg standard mass for baggage
• DO NOT forget to add in the non revenue load and also the bulk cargo load.

For the calculation:

• 99 Adults = 99 x 84 kg = 8316 kg
• 4 Children = 4 x 35 kg = 140 kg
• 3 Infants on their own seat = 3 x 35 kg = 105 kg
• 52 baggage items = 52 x 13 kg = 676 kg
• Non-revenue load = 540 kg
• Cargo load = 3000 kg
• Bulk cargo = 525 kg

Traffic load = 8316 kg + 140 kg + 105 kg + 676 kg + 540 kg + 3000 kg + 525 kg = 13 302 kg.