Jill sold half her comic books then bought 16 more she now has 36 how many did she start with? me plz

Alright! In order to solve this you have to work backwards. So, you know her end total is 36. And to get to that she bought 16 books. So:

36 - 16 = 20.

So, after she sold half her books she had 20. To find how many she started with you do the opposite of dividing by 2, multiplying by 2. So:

20 x 2 = 40.

She started with 40 books.

Let us assume the number of books with which Jill started = x
Number of books that Jill sold first is half and then Jill again bought 16 books, making her total number of books to 36.
Then
(x/2) + 16 = 36
(x/2) = 36 - 16
(x/2) = 20
x = 20 * 2
   = 40

From the above deduction, it can be easily concluded that the number of books that Jill started with was 40. I hope that the procedure is clear enough for you to understand.