Arrange X people at most, because 800*30=24000 is less than 28000, so X is greater than 30.

《800- 10(X-30)》X & lt； =28000

1 100x- 10x^2<； =28000

10(x^2- 1 10x+3025)-2250<； =0

10(x-55)^2<； =2250

(x-55)^2<； =225

x-55 & lt； = 15

x & lt=70

So the maximum x is 70. In other words, up to 70 people can travel.

I hope I can help you.

Sorry, I forgot one condition. "The per capita cost must not be less than 500", so this answer is incorrect.