Harry took 6 hours to travel from Country Q to Country R at 64 km/h. Then he travelled from Country R to another country at 1.5 times his original speed. 25% of the distance from Country Q to Country R is equal to ¹₄ of the distance from Country R to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country Q to Country R
= 6 x 64
= 384 km

Speed from Country R to another country
= 1.5 x 64
= 96 km/h

25% = ²⁵₁₀₀ = ¹₆

¹₄ Distance from Country Q to Country R = ¹₄ Distance from Country R to next country
¹₄ Distance from Country Q to Country R = ¹₄ Distance from Country R to next country

4 u = 384
1 u = 384 ÷ 4 = 96

Distance from Country R to the next country
= 4 u
= 4 x 96
= 384 km

Time taken from Country R to the next country
= 384 ÷ 96
= 4 h

Total distance of the whole journey
= 384 + 384
= 768 km

Total time taken for the whole journey = 6 + 4 = 10 h

Average speed of the whole journey
= 768 ÷ 10
= 76 ⁸₁₀
= 76 ⁴₅ km/h

Answer(s): 76 ⁴₅ km/h