Answer:
89 adult tickets were sold
Explanation:
The problem tells you that 2 of every 3 tickets sold were student tickets. So 1/3 of the tickets sold were adult tickets.
(1/3)·269 tickets = 89 tickets
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When a problem statement tells you the ratio of different items, it often turns out to be convenient to group the items using that ratio. Here, since 2 student tickets were sold for each adult ticket, that means a convenient group is 1 adult ticket and 2 student tickets, a total of 3 tickets. Now, anything to do with numbers of tickets can be figured on the basis of there being 267/3 = 89 groups. In 89 groups of tickets, there will be 89 adult tickets.