Answer:
the girl lost $30
Explanation:
she bought it for 10 but when she sold it for 15 she only got 5 dollars back. so she's still down 5.
Then she buys it for 20 and then sells it for 25. when she does this she again only gets 5 dollars back.
She lost 10 the first time and another 20 the next.
so in total she lost 30 dollars