A van 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 van covered only ⁵₇ of the journey. The speed of the Lamborghini was 20 km/h more than the speed of the van. Find the speed of the van.
Extra distance covered by the Lamborghini in 4 h
= 4 x 20
= 80 km

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

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

2 u = 80

1 u = 80 ÷ 2 = 40

Distance covered by the van when the Lamborghini reached Town R
= 5 u
= 5 x 40
= 200 km

Speed of the van
= 200 ÷ 4
= 50 km/h

Answer(s): 50 km/h