Answer:
1/10
Explanation:
First, you have to get common denominators, so we will use 10. She read 5/10 in the morning, so that is 5/10 of the book left. 2/5 = 4/10 left, so if you added those two numbers up, you only get 9/10. So this means that she read 1/10 at night. I hope this helps!