Tính hợp lý:
a) A= \(\frac{101}{19}\). \(\frac{61}{218}\)\(-\) \(\frac{101}{218}\). \(\frac{42}{19}\)+ \(\frac{117}{218}\)
b) B= \(\left(\frac{5}{2011^2}+\frac{7}{2012^2}-\frac{9}{2013^2}\right)\). \(\left(\frac{4}{5}-\frac{3}{4}-\frac{1}{20}\right)\)