2007 AMC 8 Problem 17

A mixture of 30 liters of paint is 25\% red tint, 30\% yellow tint and 45\% water. Five liters of yellow tint are added to the original mixture. What is the percent of yellow tint in the new mixture?

\textbf{(A)}\ 25 \qquad \textbf{(B)}\ 35 \qquad \textbf{(C)}\ 40 \qquad \textbf{(D)}\ 45 \qquad \textbf{(E)}\ 50

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.