At 8 a.m., Japheth started from City R and travelled towards City S and his speed remained constant throughout. At 9 a.m., Cathy started her journey from City R towards City S at an average speed of 90 km/h. Cathy overtook Japheth at 2 p.m. After overtaking, Cathy carried on her journey at the same average speed and reached at City S at 5:40 p.m.

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

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

Distance that Cathy had travelled until Cathy overtook Japheth
= 5 x 90
= 450 km

From 8 a.m. to 2 p.m. = 6 h

Japheth's average speed
= 450 ÷ 6
= 75 km/h

(b)
From 9 a.m. to 5:40 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 90
= ²⁶₃ x 90
= 780 km

Answer(s): (a) 75 km/h; (b) 780 km