Question 4107
Lines that are perpendicular have slopes that are the negative reciprocal of each other.

1)  For the given line:  y = -3x + 4   The slope here is -3.
  The slope of the perpendicular line is -(1/-3) = 1/3

2) Parallel lines have slopes that are equal.  For the given line -4x + 8 = 11
Rewrite this as:  x = -3/4 
 This is a vertical line (parallel to the y-axis).  Vertical lines have undefined slopes, so any line that is parallel to this one is also vertical and, therefore, will have an undefined slope.