Question 12
For the first part of a journey, Group B walks while A takes the bus; for the second, A walks while B takes the bus. The bus speed is $40\,\mathrm{km/h}$ when loaded and $50\,\mathrm{km/h}$ when empty. Walking speed is $4\,\mathrm{km/h}$. Both groups arrive together. Find walking distance as a fraction of bus distance.