Tính nhanh:

$\begin{array}{l}a)\frac{4}{3}+\frac{3}{5}+\frac{7}{3}+\frac{2}{5}+\frac{1}{3}\\ \\ b)\frac{2}{7}+\frac{-3}{8}+\frac{4}{7}+\frac{1}{7}+\frac{-5}{8};\\ \\ c)\frac{-5}{9}+\frac{8}{15}+\frac{-2}{11}+\frac{4}{-9}+\frac{7}{15};\\ \\ d)\frac{4}{45}+\frac{-1}{15}+\frac{7}{45}+\frac{4}{15}+\frac{-2}{45}+\frac{-1}{5}\end{array}$