Let the time taken by A to cover 1 km = $$x$$ seconds
Time taken by B and C = $$x$$ + 30 seconds and $$x$$ + 45 seconds
$$\eqalign{
& \frac{x}{{x + 45}} = \frac{{41}}{{50}} \cr
& 50x = 41x + 1845 \cr
& x = 205{\text{ seconds}} \cr} $$
42.
In a 400 metre race, A runs at a speed of 16 m/sec. If A gives B a start of 15 metres and still beats him by 10 sec, then what is the speed of B?