2.514. Найдите значение выражения: а) \(\dfrac{3,1}{1,7}+\dfrac{6,7}{5,1}\); б) \(\dfrac{2,5}{4,4}+\dfrac{4,6}{13,2}\); в) \(\dfrac{6,8}{7,2}-\dfrac{2,7}{3,6}\); г) \(\dfrac{2,4}{7,7}-\dfrac{2,8}{12,1}\).

а) \(\dfrac{3,1}{1,7}+\dfrac{6,7}{5,1}=\dfrac{31}{17}+\dfrac{67}{51}=\dfrac{93+67}{51}=\dfrac{160}{51}\).

б) \(\dfrac{2,5}{4,4}+\dfrac{4,6}{13,2}=\dfrac{25}{44}+\dfrac{23}{66}=\dfrac{75+46}{132}=\dfrac{121}{132}\).

в) \(\dfrac{6,8}{7,2}-\dfrac{2,7}{3,6}=\dfrac{17}{18}-\dfrac{3}{4}=\dfrac{34-27}{36}=\dfrac{7}{36}\).

г) \(\dfrac{2,4}{7,7}-\dfrac{2,8}{12,1}=\dfrac{24}{77}-\dfrac{28}{121}=\dfrac{264-196}{847}=\dfrac{68}{847}\).

Ответ: а) \(\dfrac{160}{51}\); б) \(\dfrac{121}{132}\); в) \(\dfrac{7}{36}\); г) \(\dfrac{68}{847}\).