Rael took 5 hours to travel from Country C to Country D at 80 km/h. Then he travelled from Country D to another country at 1.5 times his original speed. 70% of the distance from Country C to Country D is equal to ¹₃ of the distance from Country D to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country C to Country D
= 5 x 80
= 400 km

Speed from Country D to another country
= 1.5 x 80
= 120 km/h

70% = ⁷⁰₁₀₀ = ⁷₅

⁷₁₀ Distance from Country C to Country D = ¹₃ Distance from Country D to next country
⁷₁₀ Distance from Country C to Country D = ⁷₂₁ Distance from Country D to next country

10 u = 400
1 u = 400 ÷ 10 = 40

Distance from Country D to the next country
= 21 u
= 21 x 40
= 840 km

Time taken from Country D to the next country
= 840 ÷ 120
= 7 h

Total distance of the whole journey
= 400 + 840
= 1240 km

Total time taken for the whole journey = 5 + 7 = 12 h

Average speed of the whole journey
= 1240 ÷ 12
= 103 ⁴₁₂
= 103 ¹₃ km/h

Answer(s): 103 ¹₃ km/h