$A$ trader buys goods at a $20 \%$ discount on the marked price. If he wants to make a profit of $25 \%$ after allowing a discount of $20 \%$ on his new marked price,by what percent should his new marked price be greater than the original marked price?

$A$ 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 $\%$)

In these questions,two equations numbered $I$ and $II$ are given. You have to solve both the equations and mark the appropriate option.
$I.$ $3x^2 - 13x + 12 = 0$
$II.$ $2y^2 - 15y + 28 = 0$

$A$ merchant buys $4000 \, kg$ of wheat,one-fifth of which he sells at a gain of $5 \%$,one-fourth at a gain of $10 \%$,one-half at a gain of $12 \%$,and the remainder at a gain of $16 \%$. If he had sold the whole at a gain of $11 \%$,he would have made $Rs. 72.80$ more. What was the cost price of the crop per $kg$? (in $Rs.$)

$A$ businessman allows a discount of $10 \%$ on the marked price. What percent above the cost price must he mark his goods to make a profit of $17 \% ?$

$A$ man bought oranges at the rate of $8$ for $Rs. 34$ and sold them at the rate of $12$ for $Rs. 57$. How many oranges should be sold to earn a net profit of $Rs. 45$?