At 7 a.m., Luis started from City T and travelled towards City U and his speed remained constant throughout. At 9 a.m., Sabrina started her journey from City T towards City U at an average speed of 84 km/h. Sabrina overtook Luis at 1 p.m. After overtaking, Sabrina carried on her journey at the same average speed and reached at City U at 4:50 p.m.

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

(a)
From 9 a.m. to 1 p.m. = 4 h

Distance that Sabrina had travelled until Sabrina overtook Luis
= 4 x 84
= 336 km

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

Luis's average speed
= 336 ÷ 6
= 56 km/h

(b)
From 9 a.m. to 4:50 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 84
= ⁴⁷₆ x 84
= 658 km

Answer(s): (a) 56 km/h; (b) 658 km