\[18xy + 6x - 24y - 8 =\]
\[= 6x \cdot (3y + 1) - 8 \cdot (3y + 1) =\]
\[= (3y + 1) \cdot (6x - 8)\]
\[при\ x = 1\frac{2}{3} = \frac{5}{3};y = 0,4:\]
\[(3 \cdot 0,4 + 1) \cdot \left( \frac{6 \cdot 5}{3} - 8 \right) =\]
\[= (1,2 + 1) \cdot \left( \frac{2 \cdot 5}{1} - 8 \right) = 2,2 \cdot 2 = 4,4.\]
\[Ответ:4,4.\]