Peter took 4 hours to travel from Country H to Country J at 60 km/h. Then he travelled from Country J to another country at 1.4 times his original speed. 70% of the distance from Country H to Country J is equal to ¹₅ 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
= 4 x 60
= 240 km

Speed from Country J to another country
= 1.4 x 60
= 84 km/h

70% = ⁷⁰₁₀₀ = ⁷₄

⁷₁₀ Distance from Country H to Country J = ¹₅ Distance from Country J to next country
⁷₁₀ Distance from Country H to Country J = ⁷₃₅ Distance from Country J to next country

10 u = 240
1 u = 240 ÷ 10 = 24

Distance from Country J to the next country
= 35 u
= 35 x 24
= 840 km

Time taken from Country J to the next country
= 840 ÷ 84
= 10 h

Total distance of the whole journey
= 240 + 840
= 1080 km

Total time taken for the whole journey = 4 + 10 = 14 h

Average speed of the whole journey
= 1080 ÷ 14
= 77 ²₁₄
= 77 ¹₇ km/h

Answer(s): 77 ¹₇ km/h