$'A ^{\prime}$ 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 $Rs.$)

A shopkeeper sold two bicycles for $Rs.\,1500$ each. On one, he gains $25 \%$ and on the other he loses $20 \%$. His gain or loss per cent in the whole transaction is

A fruit seller sells $\frac{3}{5}$ th part of fruit at a profit of $10 \%$ and remaining at a loss of $5 \% .$ If the total profit is $Rs.\, 1500$ then what is the total cost price of fruit in $Rs.$?

Ravipurchases $90$ pens and sells $40$ pens at a gain of $10 \%$ and $50$ pens at a gain of $20 \% .$ Had he sold all of them at a uniform profit of $15 \%$ he would have got $Rs.\, 40$ less. Find the cost price of each pen in $Rs.$

A wholesaler had $200$ dozens of mangoes. He sold some of these mangoes at $20 \%$ profit and the rest at $10 \%$ profit, so that he made $13 \%$ profit on selling all the mangoes. How many mangoes (in dozens) did he sells at $20 \%$ profit?

The cost price of $20$ articles is the same as selling price of $x$ articles. If the profit is $25 \%,$ then the value of $x$ is