Question

Two planes which are 1680 miles apart fly toward each other. Their speeds differ by 40 mph. If they pass each other in 2 hours what is the speed of each?

Answer 1

Answer:

Speed of slower plane = 400 mph

Speed of the faster plane = 440 mph

Step-by-step explanation:

Let x be the speed of the slower plane, in mph.

Thus;  the speed of the other plane is x +40 mph.

The distance between two planes decreases at the rate;

x + (x+40) = 2x + 40 mph.

We get the equation

1680/(2X + 40) = 2.

Solve the equation;  

We multiply both sides by (2x + 40), to get

1680 = 2*(2x + 40),  

1680 = 4x + 80,

4x = 1600.

Hence,

x = 1600/4  

  = 400 mph.

Therefore; the speed of the slower airplane is 400 mph, while

The speed of the faster is 400 + 40 = 440 mph.