This is regarding a verbal math problem A Shopkeeper buys sweets at 11 for a rupee. He bought an equal number of sweets at 10 for a rupee. he sold all the sweets at 8 for a rupee. find loss or gain %

Please solve this for me. I am not able to understand this statement. Can you also explain the meaning of this problem statement ?
My previous answer was totally wrong and I apologize. Let me start again.

Per unit, the shopkeeper pays $\frac{1}{11}$ for the first kind of sweets and $\frac{1}{10}$ for the second kind of sweets. This makes an average value of $\frac{21}{220}$ when he buys. When he sells the sweets, he charges $\frac{1}{8}$ per unit. The difference is then $\frac{1}{8}-\frac{21}{220}=\frac{13}{440}$ and this is the profit per unit. Then, dividing the profit per unit by the price paid per unit, this gives $\frac{13}{42}$ which is almost $31$ percents.
He bought each sweet for 100 paisa/10 = 10 paisa;
he sold each sweet for 100 paisa/8 = 12.5 paisa.

So the gain% = ( (buying price - selling price) * 100 ) / selling price.