Tommy took 4 hours to travel from Country Q to Country R at 70 km/h. Then he travelled from Country R to another country at 1.5 times his original speed. 60% of the distance from Country Q to Country R is equal to ¹₅ 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
= 4 x 70
= 280 km

Speed from Country R to another country
= 1.5 x 70
= 105 km/h

60% = ⁶⁰₁₀₀ = ³₄

³₅ Distance from Country Q to Country R = ¹₅ Distance from Country R to next country
³₅ Distance from Country Q to Country R = ³₁₅ Distance from Country R to next country

5 u = 280
1 u = 280 ÷ 5 = 56

Distance from Country R to the next country
= 15 u
= 15 x 56
= 840 km

Time taken from Country R to the next country
= 840 ÷ 105
= 8 h

Total distance of the whole journey
= 280 + 840
= 1120 km

Total time taken for the whole journey = 4 + 8 = 12 h

Average speed of the whole journey
= 1120 ÷ 12
= 93 ⁴₁₂
= 93 ¹₃ km/h

Answer(s): 93 ¹₃ km/h