Question

A freight train travels at 30 mph. If the freight train is 300 miles ahead of an express train traveling at 55 mph, how long will the express train take to overtake the freight train?
Which equation could be used to find the number of miles the trains will travel?

A. 30x = 55(x + 300)

B. x÷30 = (x - 300)÷55

C. x÷30 = (x + 300)÷55

Answer 1

Distance<-------------300--------------><-------------------x----------------->
          ⊕---------------------------------⊕--------------------------------------⊕                      Express                                  Freight                            Overtaking point
   Speed 55                              speed 30

Let x be the distance travelled by Freight until the point of overtaking
Time = Distance/Speed, then:

Time (freight) = Distance (fright)/Speed (freight) And
Time (Express) = Distance (Express)/Speed (Express).
Now plug in the relative number:

Time (freight) = x/30  and Time (express) = (x+300)/55. But note that both times are equal, then:
x/30 = (x+300)/55 OR (x÷30 = (x+300)÷55) [Answer C]
Now let's find the distance x. Cross multiplication;

55x= 30(300+x) →55x = 9,000 + 30x
55x - 30x = 9,000 → 25x = 9,000 and x = 9,000/25 = 360 miles
Time needed for Freight to travel 360 m = 360/30= 12 Hours
Time needed for Express to travel (300+360) m = 660/55= 12 Hours
As you see, it's the same time of 12 hours
Don't forget that Distance = Speed x time or time = Distance/Speed, etc.

Answer 2

Answer:

The answer is C. x÷30 = (x + 300)÷55

Step-by-step explanation: