\[\boxed{\text{420}\text{~}\text{(420).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[если\ x = 2,6:\]
\[3x^{0} = 3 \cdot {2,6}^{0} = 3 \cdot 1 = 3.\]
\[если\ y = - 1\frac{2}{3}:\]
\[- 2,5y^{0} = - 2,5 \cdot \left( - 1\frac{2}{3} \right)^{0} =\]
\[= - 2,5 \cdot 1 = - 2,5.\]
\[если\ \ a = - 3;\ \ b = - 8:\ \]
\[10a^{2}b^{0} = 10 \cdot ( - 3)^{2} \cdot ( - 8)^{0} =\]
\[= 10 \cdot 9 \cdot 1 = 90.\]
\[если\ \ \ a = \frac{2}{3};\ \ c = - \frac{1}{3}:\]
\[27a^{0}c^{3} = 27 \cdot \left( \frac{2}{3} \right)^{0} \cdot \left( - \frac{1}{3} \right)^{3} =\]
\[= 27 \cdot \left( - \frac{1}{27} \right) = - 1.\]