Two birds leave their nest, flying in opposite directions looking for food. One bird flies 10 miles per hour faster than the other. After 4 hours they are 60 miles apart. How fast are they each flying?

10 mph and 20 mph
15 mph and 25 mph
2.5 mph and 12.5 mph
7.5 mph and 17.5 mph

Question

Two birds leave their nest, flying in opposite directions looking for food. One bird flies 10 miles per hour faster than the other. After 4 hours they are 60 miles apart. How fast are they each flying?

10 mph and 20 mph
15 mph and 25 mph
2.5 mph and 12.5 mph
7.5 mph and 17.5 mph

btaylor · Answer

60 miles/4 hours = 15 mph. So their combined speeds must equal 15. So, of your options, only 2.5 mph and 12.5 mph work.

anonymous · Answer

thank you

anonymous · Answer

Let the speed of the slower bird be x.

Speed of faster bird is x+10

The distance between them is the sum of the distance travelled by both birds.

4x + 4(x+10) = 60
4x + 4x+40 = 60
8x = 20
x= 2.5 

The speeds are 2.5mph and 12.5mph