Answer
original speed X=10
Explanation:
We know that Speed= distance/ time
Then
time =distance/speed
We were told the cyclist travels 40 km at a speed of x km/h.
Which means
Distance= 40km
speed =x km/h
Then time t =40/x
Again we we were told his speed was
reduced by 2 km/h
Then speed= (x-2)
But the Distance is still 40km
But we were told the difference in time is 1 hour
Time t=40/(x-2)
Then if we find the difference between the time t of the first condition and second condition we have
40/(x-2) - (40/x) =1
[40x-40(x-2)]/ x(x-2)= 1
80=x(x-2)
x^2-2x-80=0
This is a quadratic equation , if we solve using factorization we have
(x+8)(x-10)
x+8=0 or x-10= 0
X= -8 or 10
But we cannot have a negative value for speed then
X=10
Therefore, original speedX=10