9. Primary School No.1 and Primary School No.2 have the same number of students participating in the Golden Cup Competition. The schools use cars to transport the students to the examination site. Primary School No.1 uses cars that can seat 15 people each, while Primary School No.2 uses cars that can seat 13 people each. As a result, Primary School No.2 has to send one more car than Primary School No.1. Later, each school adds one more student to the competition, and this makes the number of cars needed by both schools the same. Finally, it is decided that each school will add one more student to the competition, and as a result, Primary School No.2 will need one more car than Primary School No.1 again. How many students from both schools will participate in the competition in the end?
9. 184 people
9.【Solution】The original number of participants from each school was a multiple of 15, and after adding 1, it became a multiple of 13. Since: $6 \times 15+1=7 \times 13$, the original number of participants from each school was: $6 \times 15=90$. In the end, the total number of participants from the two schools was: $90 \times 2+4=184$ (people) participating in the competition.