Question

Two boys on bicycles, 45 miles apart, began racing directly toward each other. The instant they started, a fly on the handle bar of one bicycle started flying straight toward the other cyclist. As soon as it reached the other handle bar it turned and started back. The fly flew back and forth in this way, from handle bar to handle bar, until the two bicycles met.

Answer 1

Complete question is: Each bicycle have speed 10 mi/h and fly flies at 21 mi/h. How far the fly flies?

Answer:

47.25 mi

Step-by-step explanation:

The relative velocity of the bicycles is 10+10 = 20 mi/h

Time in which the two bicycles meet:

$t=\frac{45}{20} = 2.25 h$

Distance covered by fly:

$d=vt\\d=21mi/h\times 2.25h \\d=47.25 mi$