Answer: 9
Step-by-step explanation:
If 19 students take history, 12 take economics and 5 take both:
19-5 = 14 students that take only history
12-5 = 7 students that take only economics
Therefore total number of students who either history, economics or history and economics: 14 + 7 + 5 = 26
Therefore students who take neither: 35 - 26 = 9