Answer:
11 units
Step-by-step explanation:
Length of side PS can be calculated using the distance formula, 
Where,
(the coordinate of P is gotten from the graph)
(given)



You can determine your speed that is Speed = (distance/Time). Mind you in this cast time should be in hour, so 30 min - 1/2 hour or 0.5 Hour
Your speed is 5/0.5 = 10 mi/hour
FORMULAS
Surface Area (Circle): Radius x Radius x 3.14 (Radius = Diameter / 2)
Surface Area (Rectangle/Square): Length x Width
Volume (Circle/Rectangle/Square): Surface Area x Average Depth x 7.5
Average Depth: (Shallow Depth + Deep Depth) ÷ 2
(Note: Constant Depth = Average Depth)