A sells an article to $B$ at a gain of $25 \%, B$ sells it to $C$ at a gain $20 \%$ and $C$ sells it to $D$ at a gain of $10 \% .$ If $D$ pays $Rs.\, 330$ for it, how much did it cost $A?$ (in $Rs.$)

A dealer buys a table listed at $Rs.\, 600$ and gets successive discount of $10 \%$ and $20 \% .$ What is his profit or loss percent if he sells at $Rs.$ $540 ?$

A tradesman gives $4 \%$ discount on the marked price and gives one article free for buying every $15$ articles and thus gains $35 \% .$ The marked price is appox. how much percent above the $CP$?

A trader marks his goods $40 \%$ above the cost price and allows a discount of $25 \% .$ The profit he makes, is in $\%$

A man bought $500$ metres of electronic wire at $50$ paise per metre. He sold $50 \%$ of it at a profit of $5 \%$ At what percent should he sell the remainder so as to gain $10 \%$ on the whole transaction?

A shopkeeper sells one transistor for $Rs.\, 840$ at a gain of $20 \%$ and another for $Rs.\, 960$ at a loss of $4 \% .$ His total gain or loss percent is