how to do this?

Question

In an island, a number of survivors have enough food to last for 5 days. After 2 days, 4 of the survivors died and the remaining food lasted for 5 more days. Find the original number of survivors...

Answer 1

If there are n survivors, there are 5n meals.

After 2 days, 2n meals have been eaten, leaving 3n

Then the 3n meals lasted the n-4 survivors 5 days:

3n/(n-4) = 5
Now just find n

Answer 2

n=10

Answer 3

How to find the n