At 9 a.m., Billy started from City G and travelled towards City H and his speed remained constant throughout. At 10 a.m., Rachel started her journey from City G towards City H at an average speed of 66 km/h. Rachel overtook Billy at 3 p.m. After overtaking, Rachel carried on her journey at the same average speed and reached at City H at 5:50 p.m.

1. Find Billy'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 Rachel had travelled until Rachel overtook Billy
= 5 x 66
= 330 km

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

Billy's average speed
= 330 ÷ 6
= 55 km/h

(b)
From 10 a.m. to 5:50 p.m. = 7 h 50 min

1 h = 60 min
7 h 50 min = 7 ⁵⁰ ₆₀
 h = 7 ⁵₆ h

Distance between the two cities
= 7 ⁵₆ x 66
= ⁴⁷₆ x 66
= 517 km

Answer(s): (a) 55 km/h; (b) 517 km