Answer:
225 adult tickets were sold
Explanation:
You are asked to find the number of adult tickets sold. It is convenient to let a variable represent that quantity. We can call it "a" to remind us it is the number of adult tickets (not student tickets).
The number of student tickets is 67 more, so can be represented by (a+67). The total number of tickets sold is the sum of the numbers of adult tickets and student tickets:
(a) + (a+67) = 517
2a + 67 = 517 . . . . . collect terms
2a = 450 . . . . . . . . . subtract 67
a = 225 . . . . . . . . . . divide by 2
There were 225 adult tickets sold.
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Check
The number of student tickets sold is ...
a+67 = 225 +67 = 292
And the total number of tickets sold is ...
225 + 292 = 517 . . . . . answer checks OK