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The ticket to a concert cost @12.30 for the lower level and $5.25 for the upper level .
A total of 12,400 tickets were sold for a total amount of $102,465. How many lower level tickets were sold ?
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Let x = the number of lower level tickets sold.
Then the number of upper level tickets is (12400-x).
The lover level tickets cost 12.30*x dollars.
The upper level tickets cost 5.25*((12400-x) dollars.
Altogether, all the tickets cost 12.30x + 5.25*(12400-x).
The equation is
12.30x + 5.25*(12400-x) = 102465.
Simplify and solve for x.