AMC 8 2007 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? $\mathrm{(A)}\ 25 \mathrm{(B)}\ 35 \mathrm{(C)}\ 40 \mathrm{(D)}\ 45 \mathrm{(E)}\ 50$