A public transport bus leaves the terminal with 2/7 of its seats empty. When it reaches the first stop, 3/5 of the bus's capacity gets on and 1/4 gets off. At the next stop, 1/3 of the bus' total seating capacity gets off. Finally, at the third stop, 3/6 get on and 1/8 get off. Are there any seats left on the bus? What fraction of the passengers must travel standing?

1. Calculate the initial passengers on the bus:
\frac{5}{7}C

2. First stop changes:
- Passengers getting on: \frac{3}{5}C
- Passengers getting off: \frac{1}{4}C

New passenger count:
\frac{5}{7}C + \frac{3}{5}C - \frac{1}{4}C = \frac{149}{140}C

3. Second stop changes:
- Passengers getting off: \frac{1}{3}C

New passenger count:
\frac{149}{140}C - \frac{1}{3}C = \frac{307}{420}C

4. Third stop changes:
- Passengers getting on: \frac{3}{6}C = \frac{1}{2}C
- Passengers getting off: \frac{1}{8}C

Final passenger count:
\frac{307}{420}C + \frac{210}{420}C - \frac{52.5}{420}C = \frac{929}{840}C

5. Check for seats left and standing passengers:
- Total passengers are \frac{929}{840}C , which is greater than \( C \).

Fraction of passengers standing:
\frac{\frac{929}{840}C - C}{\frac{929}{840}C} = \frac{89}{929}

The bus is over capacity, and \( \frac{89}{929} \) of the passengers must stand.