The sum of weights of A and B is 80 kg. 50% of A's weight is $$\frac{5}{6}$$ times the weight of B. Find the difference between their weights.

$$\eqalign{ & {\text{A}} + {\text{B}} = 80 \cr & {\text{A}} \times \frac{1}{2} = \frac{5}{6}{\text{B}} \cr & \frac{{\text{A}}}{{\text{B}}} = \frac{5}{3} \cr} $$

$$\eqalign{ & 8\,{\text{unit}} \to 80{\text{ kg}} \cr & 1\,{\text{unit}} \to 10{\text{ kg}} \cr & 2\,{\text{unit}} \to \boxed{20{\text{ kg}}} \cr} $$