List price of a book is $Rs.\,100.$ A dealer sells three such books for $Rs.\, 274.50$ after allowing discount at a certain rate. Find the rate of discount in $\%$

Nutan bought $30$ dozens of oranges for her juice stall in the school fair. She paid $Rs.\, 8$ per dozen of oranges. She also had to pay $Rs\, 500$ as the stall fee to the school authorities. She calculated that each glass'of juice would need $3$ oranges. How much should she charge per glass of juice so as to make $20 \%$ profit in $Rs?$

Tarun bought a $TV$ with $20 \%$ discount on the labelled price. Had he bought it with $25 \%$ discount, he would have saved $Rs.\,500.$ At what price did he buy the $TV?$

A discount dealer professes to sell his goods at cost price but uses a weight of $960\, gms$ instead of a $Kg$ weight. Find his gain $\% ?$

The cost price of $20$ articles is the same as the selling price of $x$ articles. If the profit is $25 \%$, then the value of $x$ is in $Rs.$