Put the values of w = 5 and x = 6 to the expression -3[w - 6² + x].
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)
3[5 - 6² + 6] = 3(5 - 36 + 6) = 3(-31 + 6) = 3(-25) = -75