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?	Choose the correct choice:
A) 2 / 5  B) 1 / 4  C) 1 / 5  D) 1 / 7  E) 2 / 3

Rationale: "let total paint = 1 let amount replaced = x 45 ( 1 - x ) + 25 x = 40 x = 1 / 4 answer : b"
Answer: B