Mrs. Silva orders \( 5 \) pizzas for every \( 20 \) students working on the campus clean-up. How many pizzas should she order if \( 36 \) students participate? How many pizzas should she order if \( 48 \) students participate? Show your work.  

(i) \( 2.25 \% \) of \( x \) is 630

Utiliza logaritmos para resolver: \( 5^{x} = 125 \).

\begin{tabular}{l} Evaluate the expression when \( c=8 \) and \( d=4 \). \\ \( \qquad \frac{48}{c}+d \) \\ \( \square \square \) \\ \hline\( \square \) \\ \hline\end{tabular}

Simplify the following: (1) \( \frac{x-1}{x^{2}+3 x+2} \div\left[\frac{x-3}{x+1}-\frac{x-4}{x+2}\right] \) (2) \( \frac{\frac{6 x+5}{x-5}}{\frac{3 x+20}{x-5}+2} \) (3) \( \frac{a^{2}+\left(1-a^{2}\right)}{(1+a) a} \times \frac{(1+a) a}{a^{2}-\left(1-a^{2}\right)} \)

Simplify. \( 6 v+3 v \)