Let G be the number of general seats sold.
Let R be the number of reserved seats sold.
The total number of seats sold is G + R = 1139
Since general seats costs $2 each, 2G is the total receipts from general tickets sales.
Since reserve seats costs $3.50 each, 3.5R is the total receipts from reserved ticket sales.
The total receipts is 2G + 3.5R = 2716
We now have two equations in two unknowns and can solve for G and R.