A seller marks his goods 30% above their cost price but allows 15% discount for cash payment. His percentage of profit when sold in cash is = ?

Let cost price of item = Rs. 100
Marked price of item = 130% of 100
$$\eqalign{ & {\text{ = 130}}\% {\text{ of 100}} \cr & {\text{ = }}\frac{{130}}{{100}} \times {\text{100 }} \cr & {\text{ = Rs}}{\text{. 130 }} \cr} $$
After discount, selling price
$$\eqalign{ & {\text{= 85}}\% {\text{ of 130 }} \cr & = \frac{{85}}{{100}} \times {\text{130 }} \cr & {\text{= Rs}}{\text{. 110}}{\text{.5}} \cr & {\text{Profit}}\% {\text{ }} \cr & = \frac{{110.50 - 100}}{{100}} \times 100{\text{ }} \cr & = 10.5{\text{ }}\% {\text{ }} \cr} $$