At 7 a.m., Zeph started from City C and travelled towards City D and his speed remained constant throughout. At 10 a.m., Gabby started her journey from City C towards City D at an average speed of 66 km/h. Gabby overtook Zeph at 1 p.m. After overtaking, Gabby carried on her journey at the same average speed and reached at City D at 6:40 p.m.

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

(a)
From 10 a.m. to 1 p.m. = 3 h

Distance that Gabby had travelled until Gabby overtook Zeph
= 3 x 66
= 198 km

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

Zeph's average speed
= 198 ÷ 6
= 33 km/h

(b)
From 10 a.m. to 6:40 p.m. = 8 h 40 min

1 h = 60 min
8 h 40 min = 8 ⁴⁰ ₆₀
 h = 8 ²₃ h

Distance between the two cities
= 8 ²₃ x 66
= ²⁶₃ x 66
= 572 km

Answer(s): (a) 33 km/h; (b) 572 km