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
Look at it this way:
When you flip a coin, the probability of it landing with EITHER side showing
is 100%.
This leads us to the rule ...
The sum of the probabilities of
all possible outcomes is 100%.
For a coin: (probability of heads) plus (probability of tails) = 100%.
That just says: We're 100% sure that the coin will land with either
heads or tails up.
An "honest" coin gets heads 50% of the time and tails the other 50%.
But if the coin is all bent and squashed and has a feather stuck to
one side and a wad of gum on the other side so that it comes up
heads 70% of the time, then the coin isn't 'honest'. But it still has to
land EITHER heads OR tails, so the sum of the probabilities is still 100%.
So the probability of heads is 30%.
ok imma help u just it should not be chem