Isolate the x. Note the equal sign, what you do to one side, you do to the other. Do the opposite of PEMDAS (Parenthesis, Exponents (& roots), Multiplication, Division, Addition, Subtraction)
First, subtract 6 from both sides
-4x + 6 (-6) = -38 (-6)
-4x = -38 - 6
-4x = -44
Next, fully isolate the x by dividing -4 from both sides