A man travels 800km partly by rail and partly by steamer. He spends 7 hours more time on steamer. If the velocity of the steamer is 20km/hr and the velocity of rail is 55km/hr, how much distance does he cover by steamer?

Let the time spent traveling by rail be t hours.
Then, the time spent traveling by steamer is (t+7) hours.

We know that Distance=Speed×Time:

Distance by rail=55×t
Distance by steamer=20×(t+7)
The total distance traveled is 800km:

55t+20(t+7)=800
55t+20t+140=800
75t=800−140
75t=660
t=
75
660
​
=
5
44
​
=8.8 hours
Now, find the distance covered by steamer:

Distance by steamer=20×(t+7)=20×(8.8+7)=20×15.8=316km