Peter took 6 hours to travel from Country G to Country H at 70 km/h. Then he travelled from Country H to another country at 1.2 times his original speed. 40% of the distance from Country G to Country H is equal to ¹₅ of the distance from Country H to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country G to Country H
= 6 x 70
= 420 km

Speed from Country H to another country
= 1.2 x 70
= 84 km/h

40% = ⁴⁰₁₀₀ = ²₆

²₅ Distance from Country G to Country H = ¹₅ Distance from Country H to next country
²₅ Distance from Country G to Country H = ²₁₀ Distance from Country H to next country

5 u = 420
1 u = 420 ÷ 5 = 84

Distance from Country H to the next country
= 10 u
= 10 x 84
= 840 km

Time taken from Country H to the next country
= 840 ÷ 84
= 10 h

Total distance of the whole journey
= 420 + 840
= 1260 km

Total time taken for the whole journey = 6 + 10 = 16 h

Average speed of the whole journey
= 1260 ÷ 16
= 78 ¹²₁₆
= 78 ³₄ km/h

Answer(s): 78 ³₄ km/h