A shopkeeper cheats to the extent of $10 \%$ while buying as well as selling, by using false weights. His total gain is in $\%$

The cost price of an article is $64 \%$ of the marked price. Calculated the gain per cent after allowing a discount of $12 \%$

A trader allows a trade discount of $20 \%$ and a cash discount of $6 \frac{1}{4} \%$ on the marked price of the goods and gets a net gain of $20 \%$ of the cost. By how much above the cost should the goods be marked for the sale? (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?

Profit earned by selling an article of $Rs.\, 1630$ is same as the loss incurred by selling the article for $Rs.$ $1320 .$ What is the $CP$ in $Rs$?

The cost price of $6$ pens is equal to the selling price of $4$ pens. Find the profit percent.