Task: Question Answering
Input (English): Problem: some of 45 % - intensity red paint is replaced with 25 % solution of red paint such that the new paint intensity is 40 %. what fraction of the original paint was replaced ?
Options: a. 2 / 5, b. 1 / 4, c. 1 / 5, d. 1 / 7, e. 2 / 3
Output (English): b