Answer:
The System of equations which represents the situations are;



Explanation:
Let the shirt sold at cost $9 be x.
Let the shirt sold at cost $11 be y.
Let the shirt sold at cost $12.50 be z.
Given:
Twice as many shirts were sold for $12.50 than were sold for $11.
Hence it means that shirt sold at at cost $12.50 were 2 times more than shirt sold at cost $11.
Hence framing in equation we get;

Now Given:
Total Shirts sold = 23
But Total Shirts sold is sum of number of shirt sold at cost $9 and number of shirt sold at cost $11 and number of shirt sold at cost $12.50.
Hence framing in equation we get;

Also Given:
Total Money made by store = $243
But Total Money made by store is sum of number of shirt sold at cost $9 Multiplied by 9 and number of shirt sold at cost $11 multiplied by 11 and number of shirt sold at cost $12.50 multiplied by 12.50.
Framing in equation form we get;

Hence the System of equations which represents the situations are;


