Monica made cookies for herself and her family. Her father ate 10 cookies and her mother ate half as much as the father. Her brother ate 2 more than her mother. How many cookies are left for Monica if she made 30 cookies in total? Let's think first. Chain of thought:
Monica's mother ate half as many cookies as Monica's father, so she ate 10 cookies / 2 = 5 cookies. Monica's brother ate 5 cookies + 2 cookies = 7 cookies. There were 30 cookies - 7 cookies - 5 cookies - 10 cookies = 8 cookies left for Monica.
Therefore, the answer is 8.