A man decides to travel 90 kilometres in 9 hours, partly by foot and partly on a bicycle. If his speed on foot is 9 kilometers/hour and bicycle is 18 kilometers/hour, what is the distance he travels on foot?

Correct option is A

Given:

Speed on foot = 9km/hr

Speed on bicycle = 18km/hr

Total distance = 90km

Total time = 9 hours

Formula Used:

Distance = Speed$$\times$$​ Time

Solution:

Let the time taken while moving on foot be $$x$$​ hrs

Then time taken on bicycle =$$(9-x)$$​hrs

According to question:

​$$x \times 9 + (9-x) \times 18 = 90$$​​

​$$9x +162 -18x =90$$​​

​$$162-90= 9x$$​​

​$$72 = 9x$$​​

x = 8 hours

Distance travelled on foot = $$9 \times 8 = \bf 72\ km$$​​