The difference between a discount of $40 \%$ on $Rs. 500$ and two successive discounts of $36 \%$ and $4 \%$ on the same amount is (in $Rs.$)

If after giving a discount of $18 \%$,a book is sold for $Rs. 1599$,what will be the marked price (in $Rs.$) of the book?

Two successive discounts of $a \%$ and $b \%$ on the marked price of an article are equivalent to a single discount of:

$Rs. 20$ is the true discount on $Rs. 260$ due after a certain time. What will be the true discount on the same amount due after half of the earlier time,the rate of interest being the same? (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 $Rs.$):

If the simple interest on $Rs. 2000$ at $5\%$ $p.a.$ is equal to the true discount on $Rs. 2500$ for the same time and at the same rate,the time is (in $years$)