3. Не выполняя вычислений, сравните: \( \begin{array}{ll}\text { a) }(-15)^{6} \text { и }(-19)^{7} ; & \text { б) }-5^{4} \text { и }(-5)^{4} \\ \text { в) } 0 \text { и }(-3,7)^{6} ; & \text { 2) } 0 \text { и }(-7,3)^{7}\end{array} \)

3. At a school, \( 40 \% \) of the sikthegrade students said that hip-hop is their favorite kind of music. If 100 sixth-gade students preler hip hop music, how many sixth-grade studer are at the school? Explain or show your reasoning.

expunencial \( \left.\left(4^{2}\right)\left(2^{3}\right)^{2 x-5}\right)=8 \)

Find \( n \), \( 3 n-6=18 n^{2} \) A) 0.654 (B) -0.488 (C) 0.654 OR -0.488 (D) No real roots

f) \( (-15 a b c+12 a b-9 a c-3 a) \div(-3 a) \)

3.18. Determine el máximo comun divisor de los enteros \( 15,18,24 \) y escríbalo como una combinación lineal de \( 15,18,24 \). 3.19. Sea \( a \in \mathbb{Z}^{+} \)tal que \( \operatorname{mcd}(240, a)=1 \), probar que \( 240 \mid a^{4}-1 \).