Question
Peter and John borrowed books in the ratio of 4:5. After they returned 7 books each, the ratio became 1:3. How many books did John borrow at first?
Answers
GPT 3.5
Let 4x be the number of books Peter borrowed initially and 5x be the number of books John borrowed initially.
The books left after returning 7 books each are (4x - 7) and (5x - 7).
The ratio of the books left is (4x - 7):(5x - 7) = 1:3
3(4x - 7) = 1(5x - 7)
12x - 21 = 5x - 7
12x - 5x = -7 + 21
7x = 14
x = <<2=2>>2
The number of books John borrowed initially is 5(2) = <<5*2=10>>10. Answer: \boxed{10}.
The books left after returning 7 books each are (4x - 7) and (5x - 7).
The ratio of the books left is (4x - 7):(5x - 7) = 1:3
3(4x - 7) = 1(5x - 7)
12x - 21 = 5x - 7
12x - 5x = -7 + 21
7x = 14
x = <<2=2>>2
The number of books John borrowed initially is 5(2) = <<5*2=10>>10. Answer: \boxed{10}.