Billy took 5 hours to travel from Country J to Country K at 56 km/h. Then he travelled from Country K to another country at 1.5 times his original speed. 65% of the distance from Country J to Country K is equal to ¹₆ of the distance from Country K to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country J to Country K
= 5 x 56
= 280 km

Speed from Country K to another country
= 1.5 x 56
= 84 km/h

65% = ⁶⁵₁₀₀ = ¹³₅

¹³₂₀ Distance from Country J to Country K = ¹₆ Distance from Country K to next country
¹³₂₀ Distance from Country J to Country K = ¹³₇₈ Distance from Country K to next country

20 u = 280
1 u = 280 ÷ 20 = 14

Distance from Country K to the next country
= 78 u
= 78 x 14
= 1092 km

Time taken from Country K to the next country
= 1092 ÷ 84
= 13 h

Total distance of the whole journey
= 280 + 1092
= 1372 km

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

Average speed of the whole journey
= 1372 ÷ 18
= 76 ⁴₁₈
= 76 ²₉ km/h

Answer(s): 76 ²₉ km/h