Помогите пожалуйста Пример 3 и пример б

3)

$\frac{-z}{0.8} = 4.5 \\ \\ -z = 4,5*0,8 \\ \\ -z = 3,6 \\ \\ z = -3,6$

б)

$\frac{-2\frac{4}{7}*6.4*(-0.45)*(- \frac{10}{11})*0.5}{\frac{3}{11}*(-0.72)*(-3 \frac{3}{7} )} = \frac{-\frac{18}{7}*\frac{64}{10} *\frac{45}{100}*\frac{10}{11}* \frac{5}{10}}{\frac{3}{11}*\frac{72}{100} *\frac{24}{7} }= \frac{-\frac{18*64*45*5}{7*100*11*10} }{\frac{3*72*24}{11*100*7}}= \\ \\ =-\frac{18*64*45*5*11*100*7}{7*100*11*10*3*72*24} }=-\frac{18*64*45*5}{10*3*72*24} }=-\frac{9*2*8*8*45*5}{5*2*3*9*8*24} } =-\frac{8*45}{3*24} }= \\ \\ =-\frac{4*2*3*5*3}{3*2*3*4} }= -5$