Jenson took 4 hours to travel from Country K to Country L at 80 km/h. Then he travelled from Country L to another country at 1.4 times his original speed. 70% of the distance from Country K to Country L is equal to ¹₃ of the distance from Country L to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country K to Country L
= 4 x 80
= 320 km

Speed from Country L to another country
= 1.4 x 80
= 112 km/h

70% = ⁷⁰₁₀₀ = ⁷₄

⁷₁₀ Distance from Country K to Country L = ¹₃ Distance from Country L to next country
⁷₁₀ Distance from Country K to Country L = ⁷₂₁ Distance from Country L to next country

10 u = 320
1 u = 320 ÷ 10 = 32

Distance from Country L to the next country
= 21 u
= 21 x 32
= 672 km

Time taken from Country L to the next country
= 672 ÷ 112
= 6 h

Total distance of the whole journey
= 320 + 672
= 992 km

Total time taken for the whole journey = 4 + 6 = 10 h

Average speed of the whole journey
= 992 ÷ 10
= 99 ²₁₀
= 99 ¹₅ km/h

Answer(s): 99 ¹₅ km/h