At 9 a.m., Glen started from City D and travelled towards City E and his speed remained constant throughout. At 10 a.m., Dana started her journey from City D towards City E at an average speed of 90 km/h. Dana overtook Glen at 2 p.m. After overtaking, Dana carried on her journey at the same average speed and reached at City E at 3:20 p.m.

1. Find Glen's average speed in km/h.
2. What is the distance between the two cities?

(a)
From 10 a.m. to 2 p.m. = 4 h

Distance that Dana had travelled until Dana overtook Glen
= 4 x 90
= 360 km

From 9 a.m. to 2 p.m. = 5 h

Glen's average speed
= 360 ÷ 5
= 72 km/h

(b)
From 10 a.m. to 3:20 p.m. = 5 h 20 min

1 h = 60 min
5 h 20 min = 5 ²⁰ ₆₀
 h = 5 ¹₃ h

Distance between the two cities
= 5 ¹₃ x 90
= ¹⁶₃ x 90
= 480 km

Answer(s): (a) 72 km/h; (b) 480 km