Angelina baked 100 cookies she ate half of the cookies and gave away 3/10 of the cookies how many cookies were left over

Angelina ate half of the cookies, which is 100/2 = <<100/2=50>>50 cookies.

She gave away 3/10 of the cookies, which is 3/10 * 100 = <<3/10*100=30>>30 cookies.
Therefore, there were 100 - 50 - 30 = <<100-50-30=20>>20 cookies left over. Answer: \boxed{20}.

Let's calculate step by step:

1. Angelina baked 100 cookies.
2. She ate half of the cookies, which is 100/2 = <<100/2=50>>50 cookies.
3. She gave away 3/10 of the cookies. This is 3/10 * 100 = <<3/10*100=30>>30 cookies.
4. To find the number of cookies left, we subtract the cookies she ate and gave away from the original number: 100 - 50 - 30 = <<100-50-30=20>>20 cookies.

Therefore, Angelina has 20 cookies left over.