What is the change of base formula for logarithms?

Expand. Your answer should be a polynomial in standard form. \( (-f+10)(3 f-1)=\square \)

What is a proportional relationship?

Expand. Your answer should be a polynomial in standard form. \( (6 f-7)(8 f-9)=\square \)

138. Hallar el resto de la división \( \frac{[(x+4)(x+3)(x+2)(x+1)+3]^{4}}{x^{2}+5 x+5} \) \( \begin{array}{lllll}\text { a. } 25 & \text { b. } 34 & \text { c. } 43 & \text { d. } 27 & \text { e. } 6\end{array} \)

b. La signora Adele oggi ha venduto un piumone a 65 euro e alcuni completini per bambini. In tutto ha incassato 275 euro. Ogni completino ha il prezzo di 35 euro. Quanti completini ha venduto?