For every adult, there must be at least one student.
let x be student, let y be adult
y = 2x
y + x = 240
5x + 10y = maximum amount.
plug in 2x for y
2x + x = 240
3x = 240
3x/3 = 240/3
x = 240/3
x = 80
There are 80 students, and 160 adults.
160 adults = $1600
80 students = $400
This will generate a total of $2000 dollars
160 adults, 80 students should be your answer
hope this helps