A bus and a Lamborghini started travelling from Town Q to Town R at the same time. After 4 hours, the Lamborghini reached Town R while the bus covered only ⁵₇ of the journey. The speed of the Lamborghini was 28 km/h more than the speed of the bus. Find the speed of the bus.
Extra distance covered by the Lamborghini in 4 h
= 4 x 28
= 112 km

When the Lamborghini reached Town R:
Distance covered by the Lamborghini = 7 u
Distance covered by the bus = 5 u

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

2 u = 112

1 u = 112 ÷ 2 = 56

Distance covered by the bus when the Lamborghini reached Town R
= 5 u
= 5 x 56
= 280 km

Speed of the bus
= 280 ÷ 4
= 70 km/h

Answer(s): 70 km/h