Glen took 4 hours to travel from Country A to Country B at 60 km/h. Then he travelled from Country B to another country at 1.2 times his original speed. 60% of the distance from Country A to Country B is equal to ¹₅ 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
= 4 x 60
= 240 km

Speed from Country B to another country
= 1.2 x 60
= 72 km/h

60% = ⁶⁰₁₀₀ = ³₄

³₅ Distance from Country A to Country B = ¹₅ Distance from Country B to next country
³₅ Distance from Country A to Country B = ³₁₅ Distance from Country B to next country

5 u = 240
1 u = 240 ÷ 5 = 48

Distance from Country B to the next country
= 15 u
= 15 x 48
= 720 km

Time taken from Country B to the next country
= 720 ÷ 72
= 10 h

Total distance of the whole journey
= 240 + 720
= 960 km

Total time taken for the whole journey = 4 + 10 = 14 h

Average speed of the whole journey
= 960 ÷ 14
= 68 ⁸₁₄
= 68 ⁴₇ km/h

Answer(s): 68 ⁴₇ km/h