Neave took 6 hours to travel from Country H to Country J at 75 km/h. Then he travelled from Country J to another country at 1.2 times his original speed. 70% of the distance from Country H to Country J is equal to ¹₆ of the distance from Country J to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country H to Country J
= 6 x 75
= 450 km

Speed from Country J to another country
= 1.2 x 75
= 90 km/h

70% = ⁷⁰₁₀₀ = ⁷₆

⁷₁₀ Distance from Country H to Country J = ¹₆ Distance from Country J to next country
⁷₁₀ Distance from Country H to Country J = ⁷₄₂ Distance from Country J to next country

10 u = 450
1 u = 450 ÷ 10 = 45

Distance from Country J to the next country
= 42 u
= 42 x 45
= 1890 km

Time taken from Country J to the next country
= 1890 ÷ 90
= 21 h

Total distance of the whole journey
= 450 + 1890
= 2340 km

Total time taken for the whole journey = 6 + 21 = 27 h

Average speed of the whole journey
= 2340 ÷ 27
= 86 ¹⁸₂₇
= 86 ²₃ km/h

Answer(s): 86 ²₃ km/h