Answer:
39 children, 201 adults
Explanation:
Let c = number of children
 a = number of adults
 c + a = 240
1.50c + 2.25a = 510.75
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1.50c + 1.50a = 360
1.50c + 2.25a = 510.75
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 .75a = 150.75
 a = 201, c = 39