A lorry and a Lamborghini started travelling from Town P to Town Q at the same time. After 3 hours, the Lamborghini reached Town Q while the lorry covered only ⁵₇ of the journey. The speed of the Lamborghini was 28 km/h more than the speed of the lorry. Find the speed of the lorry.
Extra distance covered by the Lamborghini in 3 h
= 3 x 28
= 84 km

When the Lamborghini reached Town Q:
Distance covered by the Lamborghini = 7 u
Distance covered by the lorry = 5 u

Extra distance covered by the Lamborghini 
= 7 u - 5 u
= 2 u

2 u = 84

1 u = 84 ÷ 2 = 42

Distance covered by the lorry when the Lamborghini reached Town Q
= 5 u
= 5 x 42
= 210 km

Speed of the lorry
= 210 ÷ 3
= 70 km/h

Answer(s): 70 km/h