Nora read 1/4 of a book on monday and 2/5 on tuesday. what fraction of the book does she have left to read?

On Monday, Nora read ¼ of the book, therefore she is left with ¾ of the original book.

Then on Tuesday, she read 2/5 of what was left on Monday therefore she is left with 3/5 of ¾ of the original book. This is equal to:

(3/5) (3/4) = 9/20

She still needs to read 9/20 of the book or 0.45 or 45% of the book.