Howard took 5 hours to travel from Country T to Country U at 78 km/h. Then he travelled from Country U to another country at 1.5 times his original speed. 30% of the distance from Country T to Country U is equal to ¹₅ 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
= 5 x 78
= 390 km

Speed from Country U to another country
= 1.5 x 78
= 117 km/h

30% = ³⁰₁₀₀ = ³₅

³₁₀ Distance from Country T to Country U = ¹₅ Distance from Country U to next country
³₁₀ Distance from Country T to Country U = ³₁₅ Distance from Country U to next country

10 u = 390
1 u = 390 ÷ 10 = 39

Distance from Country U to the next country
= 15 u
= 15 x 39
= 585 km

Time taken from Country U to the next country
= 585 ÷ 117
= 5 h

Total distance of the whole journey
= 390 + 585
= 975 km

Total time taken for the whole journey = 5 + 5 = 10 h

Average speed of the whole journey
= 975 ÷ 10
= 97 ⁵₁₀
= 97 ¹₂ km/h

Answer(s): 97 ¹₂ km/h