Successive discounts of $10 \%, 12 \%$ and $15 \%$ amount to a single discount of

If a commission at the rate of $10 \%$ is given to a bookseller on the marked price of a book by the publisher, the publisher gains $20 \%$. If the commission is increased to $15 \%$ then the gain percent would be

A man sells each of his $2$ articles for $Rs.$ $99.$ On one he gains $10 \%$ and on the other he incurred a loss of $1 \%$ in the entire transaction. What is his total gain in $\%$?

Kritika bought $25$ $i-$pads and $i-$phones for $Rs.\, 205000.$ She sold $80 \%$ of the $i-$pads and $12$ $i-$phones for a profit of $Rs.\, 40000.$ Each $i-$pad was marked up by $20 \%$ over cost and each $i-$phone was sold at a profit of $Rs.\, 2000.$ The remaining $i-$pads and $3$ $i-$phones could not be sold. What is Kritika's overall profit$/$loss?

A man sells a scooter to his friend at $10 \%$ loss. If the friend sells it for $RS.\, 4000$ and gains $20\%,$ find out the original cost price of the scooter. (in $Rs.$)

By selling a book for $Rs.$ $360,20 \%$ profit was earned. What is the $CP$ of the book in $Rs.$?