distane rate time

Question

Two airplanes leave an airport at the same time and travel in opposite directions. One plane travels
100

/
km
h

faster than the other. If the two planes are
4860
km

apart after
3

hours, what is the rate of each plane?

Answer 1

Let x = the rate of the slower plane

Let x + 100 = the rate of the faster plane

3x + 3(x+100) = 4860

3x + 3x + 300 = 4860

6x = 4560

x = 760 mph

x + 100 = 760 + 100 = 860 mph

Answer 2

S is the speed of the slower plane.

distance = rate x time
4860 = (S+(S+100)) * 3

4860 = (2s +100) * 3

1620 = 2s + 100

1520 = 2s

s = 760


The slower plane 760
The faster plane 860

CHECK: 3( 760 + 860) = 3 * 1620 = 4860