$A$ product when sold with $10 \%$ rebate on the listed price gave a profit of $Rs$ $70$. What was its cost price? (in $Rs$)

$A$ shopkeeper sells $25$ articles at $Rs. 45$ per article after giving a $10 \%$ discount and earns a $50 \%$ profit. If no discount is given,the profit percentage gained is......$\%$

Allowing $20 \%$ and $15 \%$ successive discounts,the selling price of an article becomes $Rs. 3,060$. Then the marked price will be (in $Rs.$):

If on selling $12$ notebooks,a seller makes a profit equal to the selling price of $4$ notebooks,what is his percent profit?

$A$ dishonest dealer professes to sell his goods at cost price but uses a weight of $960 \, g$ instead of a $1 \, kg$ weight. Find his gain $\%$. (in $\%$)

$A$ man buys two chairs for a total cost of $900$. By selling one for $\frac{4}{5}$ of its cost and the other for $\frac{5}{4}$ of its cost,he makes a profit of $90$ on the whole transaction. The cost of the lower priced chair is (in $Rs.$)