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

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

(a)
From 10 a.m. to 3 p.m. = 5 h

Distance that Risa had travelled until Risa overtook Valen
= 5 x 90
= 450 km

From 9 a.m. to 3 p.m. = 6 h

Valen's average speed
= 450 ÷ 6
= 75 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) 75 km/h; (b) 480 km