First years flies = 6,692 miles ≈7000 miles.
Second year flies = 16,429 miles ≈ 16000.
Third year flies = 24,211 miles ≈ 24000
Total number of miles flies in first and second year = 7,000miles +16,000 miles
Number of more miles he flew in the third year than the first and second year combined = Number of miles flies in third year - Total number of miles flies in first and second year
Number of more miles he flew in the third year than the first and second year combined 24,000 - (7,000+16,000)
Therefore, 24,000 - (7,000+16,000) estimation of how many more miles he flew in the third year than the first and second year combined.
