At 7 a.m., Ethan started from City W and travelled towards City X and his speed remained constant throughout. At 9 a.m., Risa started her journey from City W towards City X at an average speed of 66 km/h. Risa overtook Ethan at 1 p.m. After overtaking, Risa carried on her journey at the same average speed and reached at City X at 6:40 p.m.

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

(a)
From 9 a.m. to 1 p.m. = 4 h

Distance that Risa had travelled until Risa overtook Ethan
= 4 x 66
= 264 km

From 7 a.m. to 1 p.m. = 6 h

Ethan's average speed
= 264 ÷ 6
= 44 km/h

(b)
From 9 a.m. to 6:40 p.m. = 9 h 40 min

1 h = 60 min
9 h 40 min = 9 ⁴⁰ ₆₀
 h = 9 ²₃ h

Distance between the two cities
= 9 ²₃ x 66
= ²⁹₃ x 66
= 638 km

Answer(s): (a) 44 km/h; (b) 638 km