Let Jean's speed while running = x mph
Then Jean's speed while riding will be = x+9 mph
Distance covered by running = 8 miles
Distance covered by riding = 11 miles
Total time taken to complete the race = 1.5 hours
As, 
So, time for running= 
And time for riding= 
Equation becomes:

Now, multiply every term by 2x(x+9) to clear denominators:

Simplifying it we get

Solve the quadratic equation using formula

putting a=3 , b= -11, c= -144
we get (x - 9)(3x + 16) = 0
where x=9 and x=
Neglect the negative answer as speed cannot be negative, so x = 9 mph
Hence, Jean's running speed is 9 mph and riding speed is x+9 = 9+9 = 18 mph
The correct answer is option C
The lines are perpendicular.
Answer:
A,D,E,F
Step-by-step explanation:
Domain restrictions are values of x which are not acceptable in a function.
They may be arbitrary because we simply want to ignore them. eg y = x^2 between 0 and 4
They may make no sense in the context, eg graph a compounding investment over next 20 years.
Negative values for x make sense here.
They may avoid mathematical impossibilities eg y = (x^2 - 4x) / (x - 4) which must avoid dividing by zero, so x cannot = 4.
The graph will look like the line y = x but have a hole where x= 4