Let X be the number of adults attending the concert.

The number of children attending the concert is 3*X.

The theater collected a total of 7*X + 3*(3*X) = $6,000.

Multiplying through the parentheses we get 7X + 9X = $6,000

Adding like terms we get 16X = $6,000

Dividing both sides by 16 we get X = 375, the number of adults attending the concert

The number of children attending the concert is triple this number: 375 adults * 3 children/adult = <<375*3=1125>>1125 children.

The number of people attending the concert is 375 + 1125 = <<375+1125=1500>>1500 people.

# Answer

1500
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Three times as many children as adults attend a concert on Saturday. An adult ticket costs $7 and a child's ticket costs $3. The theater collected a total of $6,000. How many people bought tickets?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
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user
1500
Three times as many children as adults attend a concert on Saturday. An adult ticket costs $7 and a child's ticket costs $3. The theater collected a total of $6,000. How many people bought tickets?
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