At 7 a.m., Japheth started from City P and travelled towards City Q and his speed remained constant throughout. At 10 a.m., Xuan started her journey from City P towards City Q at an average speed of 68 km/h. Xuan overtook Japheth at 1 p.m. After overtaking, Xuan carried on her journey at the same average speed and reached at City Q at 3:45 p.m.

1. Find Japheth'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 Xuan had travelled until Xuan overtook Japheth
= 3 x 68
= 204 km

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

Japheth's average speed
= 204 ÷ 6
= 34 km/h

(b)
From 10 a.m. to 3:45 p.m. = 5 h 45 min

1 h = 60 min
5 h 45 min = 5 ⁴⁵ ₆₀
 h = 5 ³₄ h

Distance between the two cities
= 5 ³₄ x 68
= ²³₄ x 68
= 391 km

Answer(s): (a) 34 km/h; (b) 391 km