81-8:3:4 =

Let's solve the expression step by step:

1. First, we divide 8 by 3: $$8 : 3 = \frac{8}{3}$$
2. Then, we divide the result by 4: $$\frac{8}{3} : 4 = \frac{8}{3} \cdot \frac{1}{4} = \frac{8}{12} = \frac{2}{3}$$
3. Then, we subtract the result from 81: $$81 - \frac{2}{3} = \frac{243}{3} - \frac{2}{3} = \frac{241}{3} = 80\frac{1}{3}$$

Answer: $$80\frac{1}{3}$$ or $$\frac{241}{3}$$