a total of 210 people attended the opening night of a School Musical, students tickets cost $3 each while general admission tickets cost $7.50 each. If total sales were $1,296, how many general admission tickets were sold?

x=student ticket
y=general admission tickets

X+Y=210 (*3) --> 3x+3y=630
3x+7.5y=1296
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 3x+7.5y=1296
-3x+3y=630
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4.5y=666
y=666/4.5
y=148

General Admission Tickets=148