Answer: 84 books
Explanation: Jane and Kate has total number of 42 books.
Linear equation:
Let us consider that Kate has x number of books.
Since, Jane has twice as many books as Kate.
So that, Jane has number of books = 2x
When Jane gives 14 books to Kate, they will have the same number of books.
2x = x + 14
2x - x = 14
x = 14
Total number of books = x + 2x = 3x = 3*14 = 42