By selling an article at $80 \%$ of its marked price, a shopkeeper makes a loss of $10 \% .$ What will be the profit percentage if he sells it at $95 \%$ of its marked price?

A trader marks his goods $40 \%$ above the cost price and allows a discount of $25 \% .$ The profit he makes, is in $\%$

Two discounts of $40 \%$ and $20 \%$ equal to a single discount of $\%$?

If the cost price of $20$ articles is equal to the selling price of $15$ articles, find the profit percent?

Sonal buys mangoes at the rate of $3 \,kgs$ for $Rs$. $21$ and sells them at $5$ $kgs$ for $Rs.$ $50 .$ To earn a profit of $Rs.\,102,$ he must sell how many mangoes in $kgs$?

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.