Solve the following:

a. \(-\frac{12}{18} \times -\frac{13}{18} \times -\frac{21}{30}\)

b. \(-\frac{5}{7} \times \frac{6}{10} \times -\frac{8}{15}\)

c. \(-\frac{3}{5} \times \frac{15}{30} \times \frac{20}{40}\)

d. \(-\frac{9}{27} \times -\frac{4}{5} \times -\frac{1}{3}\)

e. \(-\frac{27}{54} \div \left(-\frac{18}{20} \div \frac{6}{30}\right)\)