.53571429 exactly but if you want to round the answer is different
Sometimes there is no apparent way to factor it by hand /(the factors are decimals or imaginary). To try and factor these problems is nearly impossible in your head.
If you are using half as much milk every day, you'll never run out because you'll just keep using half as much. You still won't run out with the coffee shop problem or the refrigerator problem.
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.