Answer:the cost of one adult ticket is $6.5
Explanation:
Let x represent the number of children tickets.
Let y represent the cost of one adult ticket.
35 cents children's tickets plus 20 adults cost a total of 287.5. Converting 35 cents to dollars, it becomes 35/100 = 0.35. It means that
0.35x + 20y = 287.5 - - - - - - - - - - 1
25 cents children's tickets plus 30 adults tickets cost 307.50. Converting 25 cents to dollars, it becomes 35/100 = 0.35. It means that
0.25x + 30y = 307.5 - - - - - - - - - - 2
Multiplying equation 1 by 30 and equation 2 by 20, it becomes
10.5x + 600y = 8625
5x + 600y = 6150
Subtracting, it becomes
5.5x = 2475
x = 2475/5.5 = 450
Substituting x = 450 into equation 1, it becomes
0.35 × 450 + 20y = 287.5
157.5 + 20y = 287.5
20y = 287.5 - 157.5 = 130
y = 130/20 = 6.5