There are enough food for 50 students for 54 days -> If 1 student eat them all, it would take 50 x 54 = 2700 (days)
If it's only enough for 45 days, there would be 2700 : 45 = 60 (students)
So, there should be 60-50 = 10 students added so the food is only enough for 45 days.
