Julie read 1/2 of a book in the morning, and she read some more at night. By the end of the day, she still had 2/5 of the book left to read. How much of the book did julie read at night?

Answer: she read 1/10 of the book at night.

Step-by-step explanation:

Let x represent how much of the book that Julie read at night.

Julie read 1/2 of a book in the morning, and she read some more at night. This means that she has read

1/2 + x = (1 + 2x) / 2 of the book by night. The portion of the book remaining would be

1 - (1 + 2x) / 2 = [2 - (1 + 2x) ]/2

= (1 - 2x) / 2

By the end of the day, she still had 2/5 of the book left to read. Therefore,

(1 - 2x) / 2 = 2/5

Cross multiplying,

5 (1 - 2x) = 2 * 2

5 - 10x = 4

10x = 5 - 4 = 1

x = 1/10

1/10

Step-by-step explanation:

Julie read 5/10 in the morning and had 4/10 left to read after what she read at night. At night, she read ...

1 - 1/2 - 2/5 = 10/10 - 5/10 - 4/10 = 1/10

Julie read 1/10 of the book at night.