###Human: 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?, ### Assistant: 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 = 1125 children.
The number of people attending the concert is 375 + 1125 = 1500 people. 
 So the answer is :  1500