Rs. 250/- 

Assume that initially he had Rs. X 
He spent 1/3 for cloths =. (1/3) * X 
Remaining money = (2/3) * X 

He spent 1/5 of remaining money for food = (1/5) * (2/3) * 
X = (2/15) * X 
Remaining money = (2/3) * X - (2/15) * X = (8/15) * X 

Again, he spent 1/4 of remaining maoney for travel = (1/4) 
* (8/15) * X = (2/15) * X 
Remaining money = (8/15) * X - (2/15) * X = (6/15) * X 

But after spending for travel he is left with Rs. 100/- So 
(6/15) * X = 100 
X = 250