Carl took 6 hours to travel from Country T to Country U at 60 km/h. Then he travelled from Country U to another country at 1.6 times his original speed. 60% of the distance from Country T to Country U is equal to ¹₄ of the distance from Country U to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country T to Country U
= 6 x 60
= 360 km

Speed from Country U to another country
= 1.6 x 60
= 96 km/h

60% = ⁶⁰₁₀₀ = ³₆

³₅ Distance from Country T to Country U = ¹₄ Distance from Country U to next country
³₅ Distance from Country T to Country U = ³₁₂ Distance from Country U to next country

5 u = 360
1 u = 360 ÷ 5 = 72

Distance from Country U to the next country
= 12 u
= 12 x 72
= 864 km

Time taken from Country U to the next country
= 864 ÷ 96
= 9 h

Total distance of the whole journey
= 360 + 864
= 1224 km

Total time taken for the whole journey = 6 + 9 = 15 h

Average speed of the whole journey
= 1224 ÷ 15
= 81 ⁹₁₅
= 81 ³₅ km/h

Answer(s): 81 ³₅ km/h