26) 4c³ (x-y)² / (x-y) 40c =

$$\frac{4c^3}{(x-y)} \cdot \frac{(x-y)^2}{40c} = \frac{4c^3 (x-y)^2}{(x-y) 40c} = \frac{4c^2 (x-y)}{40} = \frac{c^2(x-y)}{10}$$