11. 1) \(6\frac{3}{7}a-8\frac{5}{8}b-\frac{2}{3}c\) при \(a=\frac{14}{15}\); \(b=2\frac{18}{23}\); \(c=-6,75\); 2) \(2\frac{4}{11}a-19,25b+\frac{4}{9}c\) при \(a=13,2\); \(b=2\frac{10}{11}\); \(c=-10\frac{1}{8}\); 3) \(36\frac{2}{3}a-4,84b+7\frac{5}{7}c\) при \(a=0,9\); \(b=3\frac{9}{22}\); \(c=3,5\); 4) \(53\frac{7}{9}a-8,2b+4\frac{17}{38}c\) при \(a=3\frac{15}{22}\); \(b=-\frac{25}{82}\); \(c=-4\frac{5}{13}\).

1) Подставим значения:

\(6\frac{3}{7}\cdot\frac{14}{15}-8\frac{5}{8}\cdot2\frac{18}{23}-\frac{2}{3}\cdot(-6,75)=6-24+4,5=-13,5\).

2) \(2\frac{4}{11}\cdot13,2-19,25\cdot2\frac{10}{11}+\frac{4}{9}\cdot\left(-10\frac{1}{8}\right)=31,2-56-4,5=-29,3\).

3) \(36\frac{2}{3}\cdot0,9-4,84\cdot3\frac{9}{22}+7\frac{5}{7}\cdot3,5=33-16,5+27=43,5\).

4) \(53\frac{7}{9}\cdot3\frac{15}{22}-8,2\cdot\left(-\frac{25}{82}\right)+4\frac{17}{38}\cdot\left(-4\frac{5}{13}\right)=198+2,5-19,5=181\).

Ответ: 1) \(-13,5\); 2) \(-29,3\); 3) \(43,5\); 4) \(181\).