Question 1208244
<pre>

Must be a physics class with such ugly numbers.

The runner and bird begin at A. The finish line is C.
It is 8.7 km from A to C.
 
    x          8.7-x
--------------------------
A        B               C 

The runner is at A and runs x km to B in the same time (t) that the bird flies
from A to C to B.  That's 8.7+(8.7-x).

DISTANCE = RATE x TIME
 
{{{system(x =2.1t,8.7+(8.7-x)=8.4t)}}}

Solve the system

{{{system(x =2.1t,17.4-x=8.4t)}}}

Solve that by substitution, get approximately t=1.66, x=3.48

The bird flies 8.7 + 8.7-x = 17.4-3.48 = 13.92 km.

Edwin</pre>