Data
Adults = 55
Students = 89
The total people in the line is 55 + 89 = 144
If every ride takes 38 people, the numbers of trips is expressed as

Due to the fact that the number is bigger than 3, we assure that the number of trips to ride all the people is t = 4
To know how many people would be on the last trip we must look at the residue of the division.
The residue is 30, which means that in the last trip it will carry only 30 people