At 7 a.m., Justin started from City E and travelled towards City F and his speed remained constant throughout. At 8 a.m., Tiffany started her journey from City E towards City F at an average speed of 84 km/h. Tiffany overtook Justin at 1 p.m. After overtaking, Tiffany carried on her journey at the same average speed and reached at City F at 2:40 p.m.

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

(a)
From 8 a.m. to 1 p.m. = 5 h

Distance that Tiffany had travelled until Tiffany overtook Justin
= 5 x 84
= 420 km

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

Justin's average speed
= 420 ÷ 6
= 70 km/h

(b)
From 8 a.m. to 2:40 p.m. = 6 h 40 min

1 h = 60 min
6 h 40 min = 6 ⁴⁰ ₆₀
 h = 6 ²₃ h

Distance between the two cities
= 6 ²₃ x 84
= ²⁰₃ x 84
= 560 km

Answer(s): (a) 70 km/h; (b) 560 km