PEMDAS = Parentheses, Exponents, Multiplication, Division, Addition, Subtraction
First, subtract the numbers in the parentheses, then multiply by 11.
(12 - 9) = (3)
3 x 11 = 33
19 + 11 - 12^2 ÷ 3(33) - 7
Now, just multiply 33 by 3, and then square 12 (12 x 12).
19 + 11 - 144 ÷ 99 - 7
Now, you can divide 144 by 99, this is an infinite number, so..
144 ÷ 99 = 1.455
19 + 11 - 1.455 - 7
Finally add, then subtract.
30 - 1.455 - 7
28.545 - 7
The final answer is 21.545.