Answer: the second option is the correct answer.
Explanation:
Let x represent the weight of Martha's book for language arts.
Martha's maths textbook weighs 4/5 of a pound less than 4 times the weight of the book that she is reading for her language arts class. This means that the weight of Martha's textbook would be
4x - 4/5
If the weight of the maths textbook is 2 1/5 pounds, converting to improper fraction, it becomes 11/5 pounds. Therefore
4x - 4/5 = 11/5
4x = 11/5 + 4/5 = 15/5 = 3
x = 3/4 of a pound