If Aditya sells an article to Nutan at $10 \%$ gain,while Nutan sells it to Manish at $20 \%$ gain at $Rs. 1914$,then what is the Cost Price in $Rs.$?

$A$ shopkeeper purchases two items for $Rs. 520$. One of them is sold at a gain of $16\%$ and the other at a loss of $10\%$,thus making no profit or loss. What is the selling price of the item sold at a loss?

$A$ shopkeeper mixes $26 \, kg$ of wheat which costs $Rs. 20$ per $kg$ with $30 \, kg$ of wheat which costs $Rs. 36$ per $kg$ and sells the mixture at $Rs. 30$ per $kg$. Find the profit percent. (in $\%$)

There is a profit of $20 \%$ on the cost price of an article. The per cent of profit, when calculated on the selling price is.......$\%$

In these questions,two equations numbered $I$ and $II$ are given. You have to solve both the equations and mark the appropriate option.
$I$. $6x^2 + 19x + 15 = 0$
$II$. $3y^2 + 11y + 10 = 0$

$A$ man purchased $150$ pens at the rate of $Rs. 12$ per pen. He sold $50$ pens at a gain of $10 \%$. The percentage gain at which he must sell the remaining pens so as to gain $15 \%$ on the whole outlay is........$\%$