30. Найдите значение выражения: 1) −7/12 : 21/24; 2) 26/32 : (−13/24); 3) −16 : (−12/15); 4) 36 : (−27/30); 5) −39/42 : 26; 6) −48/54 : (−12); 7) −1 2/9 : 1 8/36; 8) 5 3/7 : (−4 1/14).

1. \(-\frac7{12}:\frac{21}{24}=-\frac7{12}\cdot\frac{24}{21}=-\frac23\).
2. \(\frac{26}{32}:\left(-\frac{13}{24}\right)=\frac{13}{16}\cdot\left(-\frac{24}{13}\right)=-\frac32\).
3. \(-16:\left(-\frac{12}{15}\right)=16\cdot\frac{15}{12}=20\).
4. \(36:\left(-\frac{27}{30}\right)=-36\cdot\frac{30}{27}=-40\).
5. \(-\frac{39}{42}:26=-\frac{13}{14}\cdot\frac1{26}=-\frac1{28}\).
6. \(-\frac{48}{54}:(-12)=-\frac89\cdot\left(-\frac1{12}\right)=\frac2{27}\).
7. \(-1\frac29=-\frac{11}{9}\), \(1\frac8{36}=\frac{13}{9}\); \(-\frac{11}{9}:\frac{13}{9}=-\frac{11}{13}\).
8. \(5\frac37=\frac{38}{7}\), \(-4\frac1{14}=-\frac{57}{14}\); \(\frac{38}{7}:\left(-\frac{57}{14}\right)=-\frac43\).

Ответ: 1) −2/3; 2) −3/2; 3) 20; 4) −40; 5) −1/28; 6) 2/27; 7) −11/13; 8) −4/3.