To find the slope of the line given, we write the equation in slope-intercept form:

For the equation,

subtracting 3x from both sides gives

Finally, dividing both sides by 8 gives

which can be rearranged and written as

Hence, the slope of the line parallel to the given line is -3/8.
To find the slope of the perpendicular line, we have to remember that

Since m = -3/8, the above gives

Simplifying the above gives

Hence, the slope of the perpendicular line is 8/3.