Write the equation of a line that is parallel to {y=9}y=9y, equals, 9 and that passes through the point {(3,-8)}(3,−8)left parenthesis, 3, comma, minus, 8, right parenthesis.

The first thing you should know is how is the function y = 9
 The function y = 9 is a straight line whose slope is equal to zero. That is, it is a horizontal line whose domain goes from less infinity to infinity.
 A parallel line to this is:
 y = -8
 The domain of this function also goes from minus infinity to infitio, therefore, for the point (3, -8)
 
 The equation of a line that is parallel to {y = 9} and that passes through the point {(3, -8)} is: 
 y = -8

Hope this ; )