A line on a graph shows a proportional relationship between the hours worked, x, and the total pay y. Two points on the graph are located at (6, 58.50)(6, 58.50) and (9, 87.75)(9, 87.75) . What is the unit rate for the pay per hour?
$4.88 per hour
$9.75 per hour
$19.50 per hour
$29.25 per hour