Question 1114404
Reading it that way is difficult.  The description could be written better like this:


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Theatre sells x adult's tickets for $20 each, and y children's tickets for $10 each.  On one evening of a performance, 350 tickets were sold and the revenue for tickets was $5250 dollars.
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System of Equations:
{{{system(20x+10y=5250,x+y=350)}}}


A simplification,
{{{system(2x+y=525,x+y=350)}}}
and you can easily eliminate y to quickly find x.
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