Rael took 5 hours to travel from Country A to Country B at 64 km/h. Then he travelled from Country B to another country at 1.5 times his original speed. 65% 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
= 5 x 64
= 320 km

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

65% = ⁶⁵₁₀₀ = ¹³₅

¹³₂₀ Distance from Country A to Country B = ¹₆ Distance from Country B to next country
¹³₂₀ Distance from Country A to Country B = ¹³₇₈ Distance from Country B to next country

20 u = 320
1 u = 320 ÷ 20 = 16

Distance from Country B to the next country
= 78 u
= 78 x 16
= 1248 km

Time taken from Country B to the next country
= 1248 ÷ 96
= 13 h

Total distance of the whole journey
= 320 + 1248
= 1568 km

Total time taken for the whole journey = 5 + 13 = 18 h

Average speed of the whole journey
= 1568 ÷ 18
= 87 ²₁₈
= 87 ¹₉ km/h

Answer(s): 87 ¹₉ km/h