I don't get this question! Please help me!
Two cars leave from the same parking lot, one driving north and the other driving south. The first car is traveling at a speed of 72 mph and the second is traveling at a speed of 68 mph. How long will it take before they are 560 miles apart?

2 hours

4 hours

6 hours

8 hours

Question

I don't get this question! Please help me!
Two cars leave from the same parking lot, one driving north and the other driving south. The first car is traveling at a speed of 72 mph and the second is traveling at a speed of 68 mph. How long will it take before they are 560 miles apart? 

 2 hours 

 4 hours 

 6 hours 

 8 hours

anonymous · Answer

Please please help!!! I was trying to solve it but I don't understand which equation u use!

anonymous · Answer

http://openstudy.com/study#/updates/50018bbfe4b0848ddd65ff38

anonymous · Answer

$$\Delta x = V * \Delta t$$

$$\Delta x_1 = 72t$$$$\Delta x_2 = 68t$$
$$\Delta x_1+ \Delta x_2 = 560$$

560 = (72 + 68)t

t = 4

anonymous · Answer

$$D=(v_1+v_2)·T \rightarrow T=\frac{ D }{ v_1+v_2 }=\frac{ 560 }{ 72+68 }=\frac{ 560 }{ 140}=4$$

anonymous · Answer

So it's 4? How would you do that? I tried putting the equation as 72x and 68x

anonymous · Answer

you have to add velocities as the cars are moving opposite directions

anonymous · Answer

Okay thank u soo soo much!

anonymous · Answer

welcome