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

A man had a certain amount with him. He spent $20 \%$ of that to buy an article and $5 \%$ of the remaining on transport. Then he gifted $Rs.\,120.$ If he is left with $Rs.\,1,400$ the amount he spent on transport is (in $Rs.$)

$'A ^{\prime}$ sells an article to $'B ^{\prime}$ at a gain of $20 \%$ and $' B ^{\prime}$ sells it to $'C ^{\prime}$ at a gain of $10 \%$ and $'C ^{\prime}$ sells it to $'D'$ at a gain of $12 \frac{1}{2} \%$. If ${ }^{\prime} D$ ' pays $Rs.\, 29.70$ what did it cost to $'A ^{\prime} ?$ (in $Rs.$)

Nisha bought a number of oranges at $2$ for a rupee and an equal number at $3$ for a rupee. To make a profit of $20 \%$ she should sell a dozen for (in $Rs.$)

A manufacturer sells an article to a wholesale dealer at a profit of $10 \%$. The wholesale dealer sells it to a shopkeeper at $20 \%$ profit. The shopkeeper sells it to a customer for $Rs.\, 56,100$ at a loss of $15 \%$. Then the cost price of the article to the manufacturer is (in $Rs.$)