At 9 a.m., Oliver started from City B and travelled towards City C and his speed remained constant throughout. At 10 a.m., Esther started her journey from City B towards City C at an average speed of 70 km/h. Esther overtook Oliver at 2 p.m. After overtaking, Esther carried on her journey at the same average speed and reached at City C at 2:30 p.m.

1. Find Oliver'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 Esther had travelled until Esther overtook Oliver
= 4 x 70
= 280 km

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

Oliver's average speed
= 280 ÷ 5
= 56 km/h

(b)
From 10 a.m. to 2:30 p.m. = 4 h 30 min

1 h = 60 min
4 h 30 min = 4 ³⁰ ₆₀
 h = 4 ¹₂ h

Distance between the two cities
= 4 ¹₂ x 70
= ⁹₂ x 70
= 315 km

Answer(s): (a) 56 km/h; (b) 315 km