Speed of the train : distance traveled / time of the travel = 10.1/(0.5)=<span>20.2 mph. Hope this helped!</span>
The ball's velocity will be represented by the derivative of its distance function:

Now find the times

for which this is equal to 30, i.e. solve

This has two solutions,

, but only one is positive and falls in the interval
![[0,3]](https://tex.z-dn.net/?f=%5B0%2C3%5D)
. So the velocity reaches 30 cm/s when

.
The 2-point form of the equation of a line can be written as ...
... y = (y2-y1)/(x2-x1)·(x -x1) +y1
For your points, this is ...
... y = (1-5)/(3-6)·(x -6) +5
... y = (4/3)(x -6) +5
It can also be written as
... y -5 = (4/3)(x -6)
Well 21 times 2 is 42 and 1/3 of 21 is 7 so 42+7 is 49. hope this is right