$A$ fair price shopkeeper takes $10 \%$ profit on his goods. He lost $20 \%$ of his goods due to theft. What is his loss percentage (in $\%$)?

$A$ sells a bicycle to $B$ at a profit of $20 \%$ and $B$ sells it to $C$ at a profit of $25 \%$. If $C$ pays $Rs. 1500$,what did $A$ pay for it in $Rs.$?

Sarita sells a phone at a profit of $20 \%$. If she had bought it at $20 \%$ less and sold it for $Rs. 180$ less, she would have gained $25 \%$. Find the cost price of the phone in $Rs.$

$A$ shopkeeper buys a toy at $Rs. 100$ and sells it at $Rs. 125$. Another shopkeeper buys the same toy at $Rs. 125$ but sells it at $Rs. 100$. What are the respective profit and loss percentages for the two shopkeepers?

$A$ man buys an article for $Rs. 27.50$ and sells it for $Rs. 28.60$. Find the gain percent. (in $\%$)

$A$ shopkeeper sells an article at a gain of $10 \%$. Had he sold it at a loss of $20 \%$,its selling price would have been $Rs. 180$ less. What is the cost price of the article? (in $Rs.$)