Bryan took 3 hours to travel from Country C to Country D at 70 km/h. Then he travelled from Country D to another country at 1.4 times his original speed. 70% of the distance from Country C to Country D is equal to ¹₄ 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
= 3 x 70
= 210 km

Speed from Country D to another country
= 1.4 x 70
= 98 km/h

70% = ⁷⁰₁₀₀ = ⁷₃

⁷₁₀ Distance from Country C to Country D = ¹₄ Distance from Country D to next country
⁷₁₀ Distance from Country C to Country D = ⁷₂₈ Distance from Country D to next country

10 u = 210
1 u = 210 ÷ 10 = 21

Distance from Country D to the next country
= 28 u
= 28 x 21
= 588 km

Time taken from Country D to the next country
= 588 ÷ 98
= 6 h

Total distance of the whole journey
= 210 + 588
= 798 km

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

Average speed of the whole journey
= 798 ÷ 9
= 88 ⁶₉
= 88 ²₃ km/h

Answer(s): 88 ²₃ km/h