Can you please help me with these algebra questions?

[Romeo Penheiro]

1) The Acme Industrial Technical College has fallen on hard times. Last year its enrolment dropped by 20% and this year enrolment dropped another 15% from last year's. Next year the college expects to have 50% of this year's enrolment. What percentage of enrolment can be expected to drop for all 3 years?

2) Fifty white-tailed deer in a region are captured an ear-tagged, then released. Six months later, 50 more deer are captured, 35 of which are ear-tagged. Assuming the second group is representative of the deer population as a whole, what is the total population size (rounded to the nearest integer)?

3) If n/p is a positive, even integer, which of the following could be true?

I) n and p are negative integers
II) n and p are integers; n is an odd integer
III) n=p