Ivan took 4 hours to travel from Country K to Country L at 66 km/h. Then he travelled from Country L to another country at 1.5 times his original speed. 25% of the distance from Country K to Country L is equal to ¹₆ of the distance from Country L to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country K to Country L
= 4 x 66
= 264 km

Speed from Country L to another country
= 1.5 x 66
= 99 km/h

25% = ²⁵₁₀₀ = ¹₄

¹₄ Distance from Country K to Country L = ¹₆ Distance from Country L to next country
¹₄ Distance from Country K to Country L = ¹₆ Distance from Country L to next country

4 u = 264
1 u = 264 ÷ 4 = 66

Distance from Country L to the next country
= 6 u
= 6 x 66
= 396 km

Time taken from Country L to the next country
= 396 ÷ 99
= 4 h

Total distance of the whole journey
= 264 + 396
= 660 km

Total time taken for the whole journey = 4 + 4 = 8 h

Average speed of the whole journey
= 660 ÷ 8
= 82 ⁴₈
= 82 ¹₂ km/h

Answer(s): 82 ¹₂ km/h