A single discount of 50% on an article costing Rs. 10000 is better than two successive discounts of 40% and 10% by = ?

$$\eqalign{ & {\text{Single discount = 50}}\% \cr & {\text{Two successive discount}} \cr & {\text{ = 40}} + {\text{10}} - \frac{{40 \times 10}}{{100}} \cr & = 50 - 4 \cr & = 46 \cr & {\text{Difference}} \cr & = 50 - 46 \cr & = 4\% \cr & {\text{Difference amount }} \cr & {\text{ = 4}}\% {\text{ of 10000}} \cr & {\text{ = }}\frac{4}{{100}} \times 10000 \cr & {\text{ = Rs}}{\text{. 400}} \cr} $$