The number of coach tickets purchased is 3, and the number of first-class tickets purchased is 8.
Let us assume the number of coach tickets purchased is x.
And the number of first-class tickets purchased is y.
Now,
Including Sarah, a total of 11 people took the trip.
Thus,

The cost of coach tickets and first-class tickets are $210 and $1200 respectively.
The total budget for airfare for the trip is $10,230.
Therefore,
210x + 1200y = 102309
21x + 120y = 1023
Solving both the equations, we get.
x=3
y=8
Thus, The number of coach tickets purchased is 3, and the number of first-class tickets purchased is 8.