Thực hiện phép tính:

a)  $1\frac{13}{15} .0,75-\left(\frac{11}{20}+25\%\right):\frac{7}{5}$

b)  ${\left(\frac{-1}{2}\right)}^3:1\frac{3}{8}-25\%\left(-6\frac{2}{11}\right)$

Thực hiện phép tính

$\begin{array}{l}a)\left(\frac{3}{5}+\frac{-3}{4}+\frac{1}{20}\right):\frac{1}{2}-\frac{1}{2}\\ \\ b)1\frac{2}{3}:\frac{1}{6}+1\frac{1}{4}.\left(\frac{1}{2}-\frac{1}{5}\right)\\ \\ c)\mathrm{0,75}-\left(\frac{13}{11}-50\%\right):\frac{5}{11}\\ \\ d)\frac{1}{27}:{\left(\frac{-1}{3}\right)}^2+75\%.\left(-2\frac{2}{3}\right)\end{array}$