Think these sentences are correct? Please tell if they are

Could you please help me correct these sentences that I think are correct?

1 I don't know why you'd be mad that I wore such a hideous dress.
2 I can tell when she is mad.
3 She is/looks mad.
4 Look (at) how she talked to me. She was so rude.
5 If my dad buys us that. That's an extra 1000 dollars we won't have to spend ourselves.
6 What has she done for you other than cause trouble.
7 Stop letting your dad know everything isn't good between us.
8 I don't know what you could have added to make what you said less awful.
9 You have 5 percent off everything except this.
10 Since when do you care what people think?

Thank you