Answer:
6x + 2; x = 2; 6(2) + 2 = 12 + 2 = 14
Step-by-step explanation:
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
(9x^2+8x)-(2x^2+3x)
9x^2+8x-2x^2-3x
7x^2+5x
Insert 80 into the equation
1(80) / 5
80/5 = 16
617513.4668 is the answer