Vincent took 6 hours to travel from Country A to Country B at 55 km/h. Then he travelled from Country B to another country at 1.8 times his original speed. 40% of the distance from Country A to Country B is equal to ¹₆ of the distance from Country B to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country A to Country B
= 6 x 55
= 330 km

Speed from Country B to another country
= 1.8 x 55
= 99 km/h

40% = ⁴⁰₁₀₀ = ²₆

²₅ Distance from Country A to Country B = ¹₆ Distance from Country B to next country
²₅ Distance from Country A to Country B = ²₁₂ Distance from Country B to next country

5 u = 330
1 u = 330 ÷ 5 = 66

Distance from Country B to the next country
= 12 u
= 12 x 66
= 792 km

Time taken from Country B to the next country
= 792 ÷ 99
= 8 h

Total distance of the whole journey
= 330 + 792
= 1122 km

Total time taken for the whole journey = 6 + 8 = 14 h

Average speed of the whole journey
= 1122 ÷ 14
= 80 ²₁₄
= 80 ¹₇ km/h

Answer(s): 80 ¹₇ km/h