Answer: The number of general admission tickets that were sold is 148.
Step-by-step explanation: Given that a total of 210 people attended the opening night of a School Musical, where students tickets cost $3 each while general admission tickets cost $7.50 each.
The total sales were $1,296.
We are to find the number of general admission tickets that were sold.
Let x and y represents the number of student tickets and the general admission tickets respectively that were sold.
Then, according to the given information, we have

and
![3x+7.50y=1296\\\\\Rightarrow 3(210-y)+7.50y=1296~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~[\textup{Using equation (i)}]\\\\\Rightarrow 630-3y+7.50y=1296\\\\\Rightarrow 4.50y=1296-630\\\\\Rightarrow 4.50y=666\\\\\Rightarrow y=(666)/(4.50)\\\\\Rightarrow y=148.](https://img.qammunity.org/2018/formulas/mathematics/college/av6k2swr5q9ysr0mv7w9xbzm29664oy06t.png)
Thus, the number of general admission tickets that were sold is 148.