a)  \(\frac{7}{11}\) + \(\frac{3}{4}\) + \(\frac{4}{11}\) + \(\frac{1}{4}\)  = (\(\frac{7}{11}\)  + \(\frac{4}{11}\)) + (\(\frac{3}{4}\) + \(\frac{1}{4}\) ) =

\(\frac{7+4}{11}\) +  \(\frac{3 + 1}{4}\) =  \(\frac{11}{11}\) +  \(\frac{4}{4}\) = 1 + 1 =2.

b) \(\frac{72}{99}\) - \(\frac{28}{99}\) - \(\frac{14}{99}\)  =  \(\frac{72}{99}\) - (\(\frac{28}{99}\) + \(\frac{14}{99}\) ) = \(\frac{72}{99}\) - \(\frac{28 + 14}{99}\) = \(\frac{72}{99}\) - \(\frac{42}{99}\) =  \(\frac{30}{99}\) = \(\frac{30:3}{99:3}\) =  \(\frac{10}{33}\)

c) 69,78 + 35,97 +30,22 = (69,78 + 30,22) + 35,97 

= 100 + 35,97 = 135,97.

d) 83,45 - 30,98 - 42,47 = 83,45 - (30,98 + 42,47)

= 83,45 - 73,45 = 10.