Question 1180809
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A movie theater has a seating capacity of 129. 
The theater charges $5.00 for children, $7.00 for students, and $12.00 for adults. 
There are half as many adults as there are children. 
If the total sales was $930, how many children, students and adults attended?
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Let x be the number of adults.


Then the number of children is 2x, according to the condition,
and the number of students is the rest (129-x-2x) = (129-3x).


The "money" equation (the revenue equation) is


    12x + 5*(2x) + 7*(129-3x) = 930  dollars.


    12x + 10x + 7*129 - 21x = 930

    x = 930 - 7*129 = 27  is the number od adults.



<U>ANSWER</U>.  27 adults;  2*27 = 54 children and the rest (129-27-54) = 48 are students.
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Solved.


<U>The lesson to learn from the solution is THIS</U> :


<pre>
     This problem is to be solved using ONE unknown and one equation - not three.
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