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 $\%$

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

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 $\% ?$

Two third of consignment was sold at a profit of $5 \%$ and the remainder at a loss of $2 \%$. If the total profit was $Rs.\, 400$ , the value of the consignment was in $Rs.$?

A single discount, equivalent to a successive discount of $40 \%$ and $30 \%$ is in $\%$?

A dairyman pays $Rs.\, 6.40$ per litre of milk. He adds water and sells the mixture at $Rs.\, 8$ per litre, thereby making $37.5\%$ profit. The proportion of water to milk received by the customers is