The distance between Town F and Town G was 189 km. At 06 00, Eva left Town F and cycled towards Town G. Xuan left Town F and cycled towards Town G at 06 20. Xuan's cycling speed was 3 km/h faster than Eva. At 12 00, Xuan caught up with Eva. When Xuan was 21 km from Town G, she stopped to wait for Eva. How far was Eva from Xuan when she stopped to wait for him?
Duration in which Xuan cycled for before she caught up with Eva
= from 06 20 to 12 00
= 5 h 40 min
= 5 ⁴⁰₆₀ h
= 5 ²₃ h

Distance that Xuan cycled more than Eva
= 5²₃ x 3
= ¹⁷₃ x 3
= 6 km

Eva's cycling speed
= 6 x 3
= 18 km/h

Xuan's cycling speed
= 18 + 3
= 21 km/h

Distance that Xuan cycled before she stopped to wait for Eva
= 189 - 21
= 168 km

Duration that Xuan cycled for after she caught up with Eva and when she stopped to wait for Eva
= (168 ÷ 21) - 5²₃
= 8 - 5²₃
= 2¹₃ h

Distance Eva was from Xuan when she stopped to wait
= 3 x 2¹₃
= 7 km

Answer(s): 7 km