# From two cities, the distance between which 100 km 2 bicyclists left to meet each other, the speed of the first

**From two cities, the distance between which 100 km 2 bicyclists left to meet each other, the speed of the first 10 m / s, the speed of the second 15 m / s, together with the first bicyclist, a fly flew out at a speed of 25 m / s met with the second, turned around, met the first, unrolled, met with the second, unfolded until until both cyclists meet. What path did the fly fly until they meet?**

S = 100 km = 100,000 km.

V1 = 10 m / s.

V2 = 15 m / s.

Vm = 25 m / s.

Sм -?

The distance between the cities S will be the sum of the distance S1 that the first cyclist traveled before the meeting and the distance S2 that the second cyclist traveled before the meeting: S = S1 + S2.

S1 = V1 * t, S2 = V2 * t, where t is the time of their movement before the meeting.

S = V1 * t + V2 * t = (V1 + V2) * t.

t = S / (V1 + V2).

All this time t the fly flew at a speed Vm, so it flew the distance Sm = Vm * t.

Sm = Vm * S / (V1 + V2).

Sm = 25 m / s * 100,000 m / (10 m / s + 15 m / s) = 100,000 m.

Answer: the fly flew the distance Sm = 100000 m.