First we need to find the slope of the given line. And for that we need to bring the equation in y=mx +b form where m is the slope. And for that, we need to solve the given equation for y.
0.5x-5y=9
Moving 9 to the left side
0.5x-5y-9=0
Moving 5y to the right side
0.5x -9 = 5y
Getting rid of 5 by dividing both sides by 5, that is
0.1x -(9/5)=y
or y=0.1x -(9/5)
Therefore slope of the given line is 0.1 and parallel lines have same slopes. Therefore slope of the parallel line is 0.1 too .