Mrs Lee left Town P for Town Q, driving at an average speed of 60 km/h. 20 minutes later, Mr Kumar left Town Q for Town P, driving at an average speed of 80 km/h. Mrs Lee met Mr Kumar 50 minutes after she left Town P. What is the distance between Town P and Town Q? Ans: ___ km

1. Calculate the time Mrs Lee travelled

Mrs Lee travelled for $50$ minutes.
Time in hours = $\frac{50}{60} = \frac{5}{6}$ h.

2. Calculate the distance Mrs Lee travelled

Distance = Speed $\times$ Time
Distance = $60 \times \frac{5}{6} = 50$ km.

3. Calculate the time Mr Kumar travelled

Mr Kumar left $20$ minutes after Mrs Lee.
Time Mr Kumar travelled = $50 - 20 = 30$ minutes.
Time in hours = $\frac{30}{60} = \frac{1}{2}$ h.

4. Calculate the distance Mr Kumar travelled

Distance = Speed $\times$ Time
Distance = $80 \times \frac{1}{2} = 40$ km.

5. Calculate the total distance between Town P and Town Q

Total distance = Distance Mrs Lee travelled + Distance Mr Kumar travelled
Total distance = $50 + 40 = 90$ km.