1) \(\frac{24}{35}+\frac{3}{8}\); \(\frac{17}{24}+\frac{9}{24}\); \(\frac{18}{21}+\frac{2}{3}\).

1) Приведём дроби к общему знаменателю: \(\operatorname{НОК}(35,8)=280\).

\(\frac{24}{35}+\frac{3}{8}=\frac{192}{280}+\frac{105}{280}=\frac{297}{280}=1\frac{17}{280}\).

\(\frac{17}{24}+\frac{9}{24}=\frac{26}{24}=\frac{13}{12}=1\frac{1}{12}\).

\(\frac{18}{21}+\frac{2}{3}=\frac{6}{7}+\frac{2}{3}=\frac{18}{21}+\frac{14}{21}=\frac{32}{21}=1\frac{11}{21}\).

Ответ: \(1\frac{17}{280};\ 1\frac{1}{12};\ 1\frac{11}{21}\).