What was the rate of discount if a computer with a marked price of $Rs. 30,000$ was sold for $Rs. 28,000$? (in $\%$)

The $B.G.$ (Banker's Gain) on a sum due $3 \text{ years}$ at $10 \%$ per annum is $Rs. 180$. The $B.D.$ (Banker's Discount) is (in $Rs.$):

While selling a watch,a shopkeeper gives a discount of $5 \%$. If he gives a discount of $7 \%$,he earns $Rs. 15$ less as profit. The marked price of the watch is (in $Rs.$):

The holder of a bill for $Rs. 17850$ nominally due on $May 21, 1991$ received $Rs. 357$ less than the amount of the bill by having it discounted at $5 \%$. When was it discounted?

After giving a discount of $20 \%$ on an article,a shopkeeper gains $20 \%$. What is the percentage mark-up?

$A$ watch dealer pays $10 \%$ customs duty on a watch which costs $Rs.\, 500$ abroad. He desires to make a profit of $20 \%$ after giving a discount of $25 \%$ to the buyer. The marked price should be (in $Rs.$)