The total cost of $7$ pens and $5$ pencils is Rs. $50$,and the total cost of $5$ pens and $7$ pencils is Rs. $46$. Represent this as a pair of linear equations in two variables.

(A) Let the cost of one pen be $x$ and the cost of one pencil be $y$.
According to the first condition,the total cost of $7$ pens and $5$ pencils is Rs. $50$,which can be written as: $7x + 5y = 50$.
According to the second condition,the total cost of $5$ pens and $7$ pencils is Rs. $46$,which can be written as: $5x + 7y = 46$.
Thus,the pair of linear equations is:
$7x + 5y = 50$
$5x + 7y = 46$