A tradesman fixed his selling price of goods at 30% above the cost price. He sells half the stock at this price, one-quarter of his stock at a discount of 15% on the original selling price and rest at a discount of 30% on the original selling price. Find the gain percentage altogether?

Let CP = 100; then marked price = 130;
Now, revenue
  $$ = { {\frac{1}{2}} \times 130 + {\frac{1}{4}} \times 0.85 \times 130 + {\frac{1}{4}} \times 0.7 \times 130} $$
$$\eqalign{ & = 65 + 27.65 + 22.5 \cr & = 115.4 \cr & \% {\text{profit}} = \frac{{15.4 \times 100}}{{100}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 15.4\% \cr} $$