An eastbound train and a westbound train meet each other on parallel tracks heading in opposite directions. The eastbound train travels 8 miles per hour faster than the westbound train. After 2.5 hours, they are 335
miles apart. At what speeds are the two trains traveling?
Write an equation using the information as it is given above that can be used to solve this problem. Use the
variable r to represent the speed of the westbound train.
Equation:
The eastbound train is traveling
mph.
The westbound train is traveling
mph.

Gotta love these motion problems!  

d = rt is what we need here to solve this, along with some logic.  

If the EB (eastbound) train left at noon then at the end of its travels, at 8pm to be specific, it was traveling for 8 hours.  Therefore, for the EB train, t = 8.

If the WB train left at 4 pm then at the end of its travels, also at 8pm, it was traveling for 4 hours.  Therefore, for the WB train, t = 4.

The distance between the trains is given as 400 miles.  That 400 mile distance is due to the fact that each train traveled a distance of rate*time.  The distance the WB train traveled + the distance the EB train traveled = 400 miles.  Now we just need to find out the distance each traveled in its respective time frame.  

For the EB train.  We already know that t = 8.  We do not know how fast it's going, so rate is just r.  In the distance formula, d = rt:

For the WB train.  We already know that t = 4.  We do not know this rate either, but we do know that it is traveling 10 mph faster than the EB train, so rate is r + 10.  In the distance formula, d = rt:

 and

We have already determined that

so

4r + 40 + 8r = 400 and

12r + 40 = 400 and

12r = 360 so

r = 30

That means that the EB train is traveling 30 mph and the WB train then has to be traveling 40 mph.

These are quite difficult...I get it.  They drive all my students, regardless of what math level they are in, absolutely batty!!!

Step-by-step explanation:

HOPE THIS HELPS!!!

correct choice is b

step-by-step explanation:

when you calculate the average rate of change of a function, you are finding the slope of the secant line between the two points. for the function the average rate of change from point to point can be calculated as

to find the average rate of change from day 2 to day 10, note that at day 2, 8 houses were sold, so a(2,8) and at day 10, 2 houses were sold, so b(10,2). thus,