$A$ shopkeeper sells $20$ pencils for the same amount of money as he paid for $25$ pencils. What is his gain percent?

Nutan bought a watch with $24 \%$ discount. If she pays $Rs. 779$ for that watch,then what is the marked price of the watch in $Rs.$?

$A$ 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 $Rs.$)

The value of an article depreciates every year at the rate of $10 \%$ of its value. If the present value of the article is $Rs. 729$,then its worth $3$ years ago was (in $Rs.$)

Half of $100$ items were sold at a profit of $20 \%$ and the remaining were sold at a profit of $40 \%$. If all the items were sold at a profit of $25 \%$,the total profit would have been $Rs. 100$ less than the previous profit. What was the cost price (in $Rs.$) of each item?

$A$ fruit-seller buys some oranges and by selling $40 \%$ of them he realizes the cost price of all the oranges. As the oranges begin to grow over-ripe,he reduces the price and sells $80 \%$ of the remaining oranges at half the previous rate of profit. The rest of the oranges being rotten are thrown away. The overall percentage of profit is (in $\%$)