3. Three times a number is seven more than double the number. What is the number?
1 answer:
You might be interested in
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