If the $CP$ of $50$ items is equal to the $SP$ of $40$ items,then what is the profit or loss $\%$ (in $\%$)?

Sasha goes to a shop to buy a sofa set and a center table. She bargains for a $10 \%$ discount on the center table and a $25 \%$ discount on the sofa set. However,the manager,by mistake,interchanged the discount percentage figures while making the bill and Sasha paid accordingly. When compared to what she should have paid for her purchases,what percentage did Sasha pay extra,given that the center table costs $40 \%$ as much as the sofa set (in $\%$)?

Rita buys an article for $Rs. 9600$. She sold it at $12\%$ loss and gets some money,and from that money,she again buys an article and this time she gets $12\%$ profit. What was the profit or loss she got from this transaction in $Rs.$?

$A$ trader marked his goods at $20 \%$ above the cost price. He sold half the stock at the marked price,one quarter at a discount of $20 \%$ on the marked price,and the rest at a discount of $40 \%$ on the marked price. What is his total gain percentage?

$A$ discount series of $10 \%$,$20 \%$,and $40 \%$ is equal to a single discount of.......$\%$

Kamal has some apples. He sold $40\%$ more than he ate. If he sold $70$ apples,how many did he eat?