Use PEMDAS:
P Parentheses first
E Exponents (ie Powers and Square Roots, etc.)
MD Multiplication and Division (left-to-right)
AS Addition and Subtraction (left-to-right).
[tex]\dfrac{(-9+6)+15}{4}=\dfrac{-3+15}{4}=\dfrac{12}{4}=3[/tex]
