Some of 10%-intensity red paint is replaced with 20% solution of red paint such that the new paint intensity is 15%. What fraction of the original paint was replaced?  Choose the correct option
A) 2/5 B) 2/3 C) 1/2 D) 1/3 E) 1/5
Let total paint = 1   Let amount replaced = x   10 (1-x) + 20x = 15   x = 1/2   ANSWER:1/2
<result>C</result>
Some of 10%-intensity red paint is replaced with 20% solution of red paint such that the new paint intensity is 15%. What fraction of the original paint was replaced?