Q8 q18.) how many adults and students should attend to raise the maximum amount of money?

 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