Question

there are hundred students in hostel .food for all is for 20 days.if 25 more students join them ,then food last for how many days

Answer 1

if there are 100 students and food for 20 days - you have to find the ratio - so it'll be:
number of students/number of days.
this gives: 100/20 = 5. so the food lasts for 5 days.
now you have 25 more students. so the total number of students is 125.

Answer 2

Isn't this an inverse proportion ?

Answer 3

100/125 = x/20 (cross multiply)
125x = (20)(100)
125x = 2000
x = 2000/125
x = 16

I think the answer is 16 days.
I think this is an inverse proportion. I really get confused with these.