Valen took 3 hours to travel from Country X to Country Y at 70 km/h. Then he travelled from Country Y to another country at 1.2 times his original speed. 40% of the distance from Country X to Country Y is equal to ¹₆ of the distance from Country Y to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country X to Country Y
= 3 x 70
= 210 km

Speed from Country Y to another country
= 1.2 x 70
= 84 km/h

40% = ⁴⁰₁₀₀ = ²₃

²₅ Distance from Country X to Country Y = ¹₆ Distance from Country Y to next country
²₅ Distance from Country X to Country Y = ²₁₂ Distance from Country Y to next country

5 u = 210
1 u = 210 ÷ 5 = 42

Distance from Country Y to the next country
= 12 u
= 12 x 42
= 504 km

Time taken from Country Y to the next country
= 504 ÷ 84
= 6 h

Total distance of the whole journey
= 210 + 504
= 714 km

Total time taken for the whole journey = 3 + 6 = 9 h

Average speed of the whole journey
= 714 ÷ 9
= 79 ³₉
= 79 ¹₃ km/h

Answer(s): 79 ¹₃ km/h