Town A and Town B are 100 km apart. At 0800, James departs for Town B from Town A, driving at a constant speed of 70 km/h. Kim departs at the same time as James for Town A from Town B, driving at a constant speed of 50 km/h. What time will James and Kim pass each other? Answer ...

1. Find the combined speed at which the distance between them decreases.

Since they are travelling towards each other,

$\text{relative speed}=70+50=120\text{ km/h}$

2. Find the time taken before they pass each other.

$\text{time}=\frac{\text{distance}}{\text{speed}}=\frac{100}{120}=\frac{5}{6}\text{ h}$

$\frac{5}{6}\text{ h}=50\text{ min}$

3. Add the travel time to the starting time.

They start at $0800$.

$0800+50\text{ min}=0850$