Umm, this is confusing!

Remember to use PEMDAS:

Parentheses Exponent Multiplication/Division Addition/Subtraction

Here is how we can simplify the problem:

$\sqrt {(5 + 8- 9) × 3 + 36 × (1 ÷ 4) - 5}$

$\sqrt {(4) × 3 + 36 × (1 ÷ 4) - 5}$

$\sqrt { 12 + 36 × (1 ÷ 4) - 5}$

$\sqrt { 12 + 9 - 5}$

$\sqrt { 16}$

$4$

So the answer is 4! (Not 4 factorial as that looks like I just wrote.)