6.
[tex]\it a)\ \ =-\dfrac{3}{\bf\not8\ ^2}\cdot\dfrac{\bf\not 4}{15}=-\dfrac{3^{(3}}{30}=-\dfrac{1}{10}\\ \\ \\ b)\ \ =-\dfrac{\bf\not27\ ^3}{32}\cdot\dfrac{64}{\bf\not9}=-\dfrac{192}{32}=-=6[/tex]
9.
[tex]\it a)\ \ =3\cdot\dfrac{2}{6}=\dfrac{6}{6}=1\\ \\ \\ b)\ \ =\dfrac{12}{5}:2,4=2,4:2,4=1\\ \\ \\ c)\ \ -\dfrac{5}{2}[/tex]
