A lorry and a Lamborghini started travelling from Town Y to Town Z at the same time. After 4 hours, the Lamborghini reached Town Z while the lorry covered only ⁷₁₀ of the journey. The speed of the Lamborghini was 30 km/h more than the speed of the lorry. Find the speed of the lorry.
Extra distance covered by the Lamborghini in 4 h
= 4 x 30
= 120 km

When the Lamborghini reached Town Z:
Distance covered by the Lamborghini = 10 u
Distance covered by the lorry = 7 u

Extra distance covered by the Lamborghini 
= 10 u - 7 u
= 3 u

3 u = 120

1 u = 120 ÷ 3 = 40

Distance covered by the lorry when the Lamborghini reached Town Z
= 7 u
= 7 x 40
= 280 km

Speed of the lorry
= 280 ÷ 4
= 70 km/h

Answer(s): 70 km/h