2 Answers

Let's say the 50 days of meals included 3 meals per day. So 500 people eating 3 meals per day would be 500 x 3 = 1500 meals per day.  1500 x 50 = 75,000 meals

At the end of 10 days, 1500 x 10 = 15,000 meals would be gone.  Adding 300 more mouths to feed would add another 300 x 3 = 900 more meals per day. 

1500 + 900 = 2400 meals per day.  How many meals did we have left when these folks showed up?

75,000 - 15,000, so we have 60,000 meals left.  60,000 / 2400 = 25.

SO, if I figured this correctly, there would be 25 days left for each of the 800 people to have 3 meals per day.

Did the new arrivals bring their own food? Also, if the students see that they're running out of food, they might ration it so the food lasts longer.