Answer:
Cost of a package of celery = $20
Explanation:
Let, x=carrots and y= celery.
So from the given data we get 2 equations
Equation 1]:-
------------(for 9 package carrot and 12 package celery)
Equation 2]:-
---------------(for 1 package carrot and 3 package celery)
After solving equation 2 we get,
------------------------(equation 3)
Now substituting equation 3 in equation 1,





∴

------------------(equation 4)
Therefore cost of a package of celery = $20