11) \( 10000-1 \) 12) 99.91 13) \( 4 x^{2}-81 y^{4} \)

\( ( 15 x - 12 ) ^ { \circ } + 5 x - 18 = 180 \)

Solve for \( x \) if \( x=\sqrt{x+\sqrt{x+\sqrt{x+\sqrt{x+\sqrt{x+\ldots}}}}} \)

Solve for \( x \) by completing the square: \( x^{2}=-3 x+10 \)

3. Mathon went to Inkhorn Bookstore where he got a discount of P15 from a book that was marked \( 20 \% \) off. Then, he went to Lofty Bookstore to check out one of their limited edition books that is now discounted at \( 30 \% \). If Mathon got a discount on the book from the Lofty Bookstore for the same amount as the original price of the book he got from Inkhorn Bookstore, how much is the difference between the two books' original prices?

\begin{tabular}{l} 25. \begin{tabular}{l}\( -6 x+4 y \geq 8 \) \\ \( y<-x-1 \) \\ \begin{tabular}{|l|l|l|l|}\hline \\ \hline & \\ \hline\end{tabular} \\ \hline \\ \hline\end{tabular} \\ \hline\end{tabular}