1) $$c^8 \cdot c^6 = c^{8+6} = c^{14}$$.
2) $$c^5 : c^3 = c^{5-3} = c^2 $$.
3) $$(c^{-4})^{-4} \cdot c^{-18} = c^{(-4) \cdot (-4)} \cdot c^{-18} = c^{16} \cdot c^{-18} = c^{16-18} = c^{-2}$$.
Ответ: 1) $$c^{14}$$, 2) $$c^2$$, 3) $$c^{-2}$$