$A$ shopkeeper sold chairs at $Rs. 2139$ each after giving a $7 \%$ discount on the labelled price. Had he not given the discount, he would have earned a profit of $15 \%$ on the cost price. What was the cost price of each chair? (in $Rs.$)

At a cost of $60$ paise per article,Sarika produces $750$ articles. She sets the selling price such that if only $600$ articles are sold,she would have made a profit of $40 \%$ on the total outlay. However,$120$ articles got spoilt and she was able to sell $630$ articles at this price. Find her actual profit or loss percent as a percentage of the total outlay,assuming that the unsold articles are useless.

The marked price of a tape recorder is $Rs. 12,600$. $A$ festival discount of $5 \%$ is allowed on it. Further,for cash payment,a second discount of $2 \%$ is given. The cash payment,in rupees,to be made for buying it is: (in $.60$)

The cost price of $100$ books is equal to the selling price of $60$ books. The gain or loss percentage will be:

$A$ sells a good to $B$ at a profit of $10 \%$ and $B$ sells it to $C$ at a profit of $20 \%$. Find out the resultant profit percentage.

$A$ shopkeeper sells notebooks at the rate of $Rs.\, 45$ each and earns a commission of $4 \%$. He also sells pencil boxes at the rate of $Rs.\, 80$ each and earns a commission of $20 \%$. How much total commission will he earn in two weeks if he sells $10$ notebooks and $6$ pencil boxes a day? (in $Rs.$)