A bus 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 bus covered only ⁷₉ of the journey. The speed of the Lamborghini was 18 km/h more than the speed of the bus. Find the speed of the bus.
Extra distance covered by the Lamborghini in 3 h
= 3 x 18
= 54 km

When the Lamborghini reached Town Q:
Distance covered by the Lamborghini = 9 u
Distance covered by the bus = 7 u

Extra distance covered by the Lamborghini 
= 9 u - 7 u
= 2 u

2 u = 54

1 u = 54 ÷ 2 = 27

Distance covered by the bus when the Lamborghini reached Town Q
= 7 u
= 7 x 27
= 189 km

Speed of the bus
= 189 ÷ 3
= 63 km/h

Answer(s): 63 km/h