$A$ dealer fixed the price of an article $40 \%$ above the cost of production. While selling it,he allows a discount of $20 \%$ and makes a profit of $Rs. 48$. The cost of production (in $Rs.$) of the article is:

If the $CP$ of $13$ bats is $Rs. 390$,what is the selling price in $Rs.$ when it is sold at a $10 \%$ loss?

$A$ 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 $Rs.$)

If the selling price of $50$ articles is equal to the cost price of $40$ articles,then the loss or gain percent is:

$A$ toothpaste labeled at $Rs. 80$ is sold for $Rs. 68$. The rate of discount is.......$\%$

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