Steps
So firstly, we need to find how much the entire trip will cost. To do this, add the product of 16 and 35 (since tickets are 35 per student, and there are 16 students) with 960:

The total cost of the trip is $1520. Next, we know that the sweatshirts will be making a profit of $19 per article sold so divide 1520 by 19:

The students need to sell 80 sweatshirts total to get enough money for the trip. Now, to know how many sweatshirts each student needs to sell individually, divide 80 by 16 (since there are 16 students):

Answer
In short, each student must sell 5 sweatshirts to pay for the entire trip.