$A$ man gains $15 \%$ by selling a calculator for a certain price. If he sells it at triple the price,then what will be the profit percentage (in $\%$)?

Vijay sold a watch at a gain of $5 \%$. Had he sold it for $Rs. 72$ more,he would have gained $13 \%$. Find out the cost price of the watch (in $Rs.$).

$A$ shopkeeper purchased $70$ $kg$ of potatoes for $Rs. 420$ and sold the whole lot at the rate of $Rs. 6.5$ per $kg$. What will be his gain percent?

$A$ man purchases some oranges at the rate of $3$ for $₹ 40$ and the same quantity at $5$ for $₹ 60$. If he sells all the oranges at the rate of $3$ for $₹ 50$,find his gain or loss percent (to the nearest integer).

Find $SP$ when $CP = Rs. 56.25$ and $\text{Gain} = 20\%$?

Surbhi bought a combined total of $25$ i-pads and i-phones. She marked up the i-pad by $20 \%$ on the cost price,while each i-phone was marked up by $Rs. 2000$. She was able to sell $75 \%$ of the i-pads and $2$ i-phones and make a profit of $Rs. 49000$. The remaining i-pads and $3$ i-phones could not be sold by her. Find her overall profit or loss if she gets no return on unsold items and it is known that an i-phone costs $50 \%$ of an i-pad.